Space Pens write great, but watch which model you buy
585445
So, this pen writes great, that is undeniable. The stylus is a great feature as well. I've noticed some folks saying that they had issues with the quality of the stylus and it breaking easily, in my experience, that is true only if you play with the stylus quite a bit. If you are someone that fidgets and will play with that stylus tip with your fingers, then yes, you probably will break it pretty easily. If you use it just as a stylus they hold up great.

Here's where this particular model got the three stars, the barrel is half metal and half plastic, but most importantly, the threads that hold the two halves together are plastic. Those plastic threads aren't very sturdy and it is very easy to break them. If you apply any pressure to the pen you'll notice it flexing like a bow in the center where the two halves of the barrel connect. It does not take much more force to snap the threads inside and ruin this pen. Mine broke within the first 3-4 weeks of having it. Make sure you find the Cap-o-matic with stylus that is truly all metal, its list price is $27 and i sold on here for $19-20. Spend the extra few bucks for the all metal version. The all metal pen is much sturdier, looks nicer, and I think, more comfortable. The two versions write the same, great, but unless you treat your pens with kid gloves then I'd definitely recommend you look for the all metal version, you'll love it!
2939055
This is a great mini pen... it's a little bigger than the Birdy or the Zebra T-3, so it feels a little more solid in my hand. It was a little too big for my wallet, so I went with the Birdy there, but this is nice for my smallest purse.

I was only going to give it three stars because, for the price, I should be able to get a refill for this pen from somewhere. But after much Googling there was nothing. Then I took a close look at the refill and realized it uses the same refill as the Pilot Birdy. So I ordered a bunch of refills for the Birdy and my estimation of this pen went up. (I order my refills on JetPens and you can get blue, black and red, as I recall. I think you can only get black on Amazon.)

Photo shows the size comparison of three mini pens sold here on Amazon against a standard ballpoint pen.
3785496
I own 3 of these pens. I LOVE how they write. I LOVE how they feel. I LOVE the inexpensive price.

HOWEVER... The Nemosine Singularity pen has a bad tendency to crack around the edges of the cap just below the steel ring. The cap will still screw on fine, but it looks raggedy.  Therefore the pen is destined to be made a desk pen where the looks do not matter.  If you plan to carry it - be aware - inspect it upon arrival. If you see light lines perpendicular to the steel ring leading to the edge of the cap - it will crack.  Or maybe you could buy a black pen so the cap cracking cannot be seen as readily.  My recommendation? Same price point for a Pilot Metropolitan with a much sturdier cap.

JC
3408854
I confess that I am a long-time Office Supply Geek.  Every year around August/September I go to Staples and rummage through all their new organizational tools, post it notes, circa/rollabinders, journals and PENS.

I am very picky about the type of pen I use as I am a ferocious journal writer.  So far the ones who have made the cut are the Pilot Priemere 207; Pilot G2 and G6 Gel pens; Liquid Expresso; Lamy Fountain Pen.

Personally, I love what I call the "engineer nibs" -- they stick out away from the pen on a small pin-like structure.  Unfortunately, my longtime love with the Liquid Expresso nib has waned due to the fact it's writing performance appears to have changed:  thicker lines, bleeds a tad.  I even tried the Pilot Razor Extra Fine Point and it ended up depositing more ink and giving me fuzzy lines MORE SO than the Expresso Fine Point.

Then on my latest trip to Staples, I discovered Sharpie made their first pen.  No bleed-through.  No blotting.  No fuzziness.  And they aren't lying.  The lines are smooth and with a slight edge to your handwriting which gives it a hint of calligraphy styling.

They are available in packages of 4 with versions of black ink; blue ink; or multi-colored (black, blue, green, red).  I must say, Amazon's price for the 4 multi-colored at close to $20 is a surprise.  Staples had it for $12, with the black or blue set for $6.

I highly recommend this pen for serious writers and those who simply love to dabble in journaling.
1662285
Nice sturdy pen, only issue is the plastic surround on the clicker. Then I saw a review of a person that bought a zebra 402 and switched out the all metal surround and clicker. 402s are nice them selves but I write to much and press to hard for the rubber grip. After the transplant I now have the perfect all metal pen. Thanks to whomever you are!!
4057626
I know many people love these pens, but I really can't get excited about the way they write. Sure, they're much better than the ubiquitous Pilot G2, but the Energel ink is not super dark and the line skips if you don't apply consistent pressure. (I only tested the black one.)

For a colored clicky gel pen, I much prefer the Zebra Sarasa Gel Retractable , which is more consistent, skips less, and lays down a darker line: http://www.amazon.com/gp/product/B0000AQNW5/ref=cm_cr_ryp_prd_ttl_sol_2
653302
Works as expected. I suggest anyone who gets the fisher space pen to get a fine tip refill, since it's closer to what most other pens consider a medium, and the standard refill is almost a thick tip.
4399659
TWO stars for this model, 5 stars for the Pentel Energel series. Nice pen, but too heavy compared to the everyday plastic ones. My el cheapo scale shows 0.4 oz for the plastic ones and 0.7 oz for this one. It is quite noticeable if you wrote a lot. For a few years, I used the Uniball 207's all the time. Then found these Energel RTX pens and those became my new faves. However, I have been testing a few Uniball 307 pens and think they may be my new new favorites.
1837776
I love Space Pens and that's essentially what this is, re-branded by Maxpedition.  The top and bottom click together with a fair amount of force.  I can't imagine losing the bottom half, unless I failed to make sure the click connection occurred.  I could imagine some folks in a rush or distracted, not making sure enough force was exerted to engage the click.
2961952
The pen is built like a brick, writes very well, and has a nice whistle to boot.  My disappointment is with the finish being different from my first Schrade tactical pen - the SCPEN7BR Fountain Pen.  The color matches, but the fountain pen has a shiny finish and the new ballpoint pen has a matte finish.  Independent of that I would have easily given it five stars.

Am I being picky?  Yes, I am.  Three stars.
2545048
This review is for 2 types of Uni-ball 207 gel pens - Medium (4 pack of blue ink) and Micro (4 pack of 2 black, 1 red, 1 blue).

First, similarities: nice shape and rubber grip make them comfortable to hold for extended use.  Good contruction (EXCEPT the micro tips!! Read below).  Both types WILL smudge on your hand as you write (not "instant dry" like I've read in reviews - especially if you're left-handed), although the Micro tip obviously does much less.  Both use the Anti-Fraud ink (a bunch of pens do now).

(1) Uni-ball 207 gel Micro pens - 1.5 Stars out of 5.  Both of the black pens worked well enough for the first 1/3 of the ink tube, then poorly - sporadic and inconsistent ink flow - and one has died (no longer writes - something popped out of the tip and it's more of a pin head than a writing head now).  So far, knock on wood, the Red (only 1/4 ink used) and Blue (1/3 ink used) icro tip pens are working well.  Either they die due to a manufacturing glitch or they wear down from use.  They don't "glide" as I write, like reviews led me to believe. It's an average pen and certainly not worth the high price per pen.  I can't find these sold by Amazon anymore - perhaps there were a lot of defectives/returns?

(2) Uni-ball 207 Medium Blue pens 3.5 Stars out of 5.  So far these are working well and I've used one completely without a problem.  This pen writes much smoother than the Micro. It also uses ink MUCH faster. I'd like a Uni-ball tip size somewhere in the middle of Micro and Medium.

The Medium tip is the way to go, but neither type lived up to the hype I read.  I'll look for other brands of gel pens.
4476046
I use Fisher space pens for work (construction) every day for the past 10 years because of their ability to write on just about anything and while holding the pen in any direction.  Occasionally I have to order a new one because I lose them, but other than that they are very resilient and fun to use.
2391669
I've been a space pen user for >30 years. The standard model's cap fits nicely over the back of the barrel thereby elongating the pen into a "normal" pen size. The trekker will not do that. So try writing with it. Unless you have a hand the size of a 5-year old it's like writing with a stub, very uncomfortable, pretty darn useless unless you're just jotting down a word or two, maybe a phone number. You just can't use it as a pen. Bummer.
4620233
I absolutely love this pen. I have more expensive space pens and a few more expensive pens from other companies. I always seem to fall back on this one. I had one when I was a child and lost it so recently decided to try another one. Seems to me (as far as I can remember) that not much has changed. Clip seems to be on there pretty well, almost seems like its bonded on with the matte black overcoat they put on the pen/clip. After reading a few of the other reviews I think I may have got a good one.. This thing writes extremely smooth, even compared to the 2 other space pens I have. This is hands down the smoothest of the bunch.
382092
PROS: This pen writes beautifully. I love the nib - it writes sharp as a scalpel. I've been told that Japanese nibs tend to be a size smaller than western manufacturers and after this pen I think that's true. This pen feels comfortable in my hand. It's just a tad larger than my other models but it's smooth curves and lightweight construction is comfortable during long writing sessions.

CONS: I don't like the non-standardized ink cartridges and the converter this pen came with is garbage. Included w/ this pen is an odd squeeze sponge converter that doesn't inspire confidence. After market converters are available but Pilot discontinued their CON-50 converter and went with the smaller CON-40, which holds less ink. Forums show users generally dislike both but preferred the CON-50s. Many Pilot Metro users end up using syringes to refill the disposable cartridges because it's easier than using either converter.
1898742
I'm a biologist, and I often have to write  in inclement conditions, so I wanted an all-weather pen with a pressurized cartridge. But I'm also a bit of a pen geek, and I like smooth-writing pens that leave a nice line. I tried a Fisher Space Pen, and found that while it was reliable in bad conditions, it wrote like a cheapo Bic Round Stic.  Too light and fine for my taste, and with lots of friction on the page.  Even when I tried a bold cartridge, it felt like the pen was constantly fighting me, and it was hard to write quickly or neatly. Sorry Fisher, I like the US-made aspect, but it seems like that cartridge design needs to be updated for modern tastes.

The Power Tank hits all the marks.  It's a very smooth writer, leaving a nice solid line with little effort or pressure.  Maybe just a touch more friction than my favorite desk writer, the Uni-Ball Jetstream. But it's close, which is surprising, considering that it uses a grease-based ink while the Jetstream is dye-based. Very little smudging or skipping. In fact, I'm on the fence about whether the Power Tank will dethrone the Jetstream as my new favorite writer.  It will definitely be a take-everywhere pen for me.

The 1.0mm point is a nice strong line, but not too wide or sloppy - just right for my taste.  I haven't tried the 0.7mm version.

UPDATE: Five months later, this is without question my favorite pen for any use.  It's the one I never lend out... I only give it out as a gift, to someone who really deserves it.  I have used several until they ran completely out of ink, and they worked right up until the last bit. My family also loves them. Time to order more!
832882
Update:
After 3 years happy with my purchase, I tried to buy this pen again. False advertising -- the current model is not the same pen! The inserts are different, the pen is shorter and even cheaper than the last model, the weight is even lighter which I dislike...  Not Recommended!! Will not repurchase.

----

Prev Review Nov 2012
I've tried several different stylus styles - here are the pros / cons of this one:

Pros:

- Thin profile - easy to hold.
- Fabric mesh nib - lasts longer, smoothe easy writing flow, best on the market
- Twist style - no need to fight with or lose a cap; several I tried the cap didn't even fit over the end!
- Length - great hand-feel, not too short like many others are

Cons:

- Weight - it's lighter than I like, especially considering it has a pen inside
- No way to attach it to the iPad - other styles have the ear-jack lanyard to keep you from losing the pen

All in all, this is among my top 2 pens, I just wish it had a bit more heft / felt less cheap.