the wide angle is not as bad but some vignetting is still noticeable
585810
This lens create a lot of vignetting, I am considering returning however the price is low enough it may not be worth it, I am using it on a Samsung Rugby. I also bought another lens and do not have this issue.
The other lens is a "Pocket Lens"

The attached picture is with the fish eye, the wide angle is not as bad but some vignetting is still noticeable, it is evident under close examination of each lens that these have a smaller aperture on the outside when compared to the Pocket lens. In either case these are cheap lens and don't expect great results.
659813
The mirror is slightly distorted, so sometimes it is difficult to see if I'm looking at a slight angle
724639
The privacy aspect of the screen works pretty well. Anyone more than 30-45 degrees off center from my monitor can't see what I'm doing. However, all of my widescreen monitor is visible to me. The filter darkens the monitor a bit, but my monitor is bright enough that it's not a problem. The first of my two complaints is price. It's difficult to understand why a piece of plastic is so expensive. The second, minor complaint is that it doesn't quite fit my monitor. There's a 1/4 to 1/2 inch gap at the top. That's true even though I went through 3M's sizing Web site. If you really need privacy, it does what it advertises.
3253901
I like the wide angle and fairly decent image at night time. Please be aware that this only takes up to 32 gb of micro SD. I bought a 64 gb micro sd and it would not tell me that it was not recording or that it's not compatible, it just keep pretending to record until I tried to look at the result, than I realized nothing was recorded.
1989699
The optics are clear, the mount and tripod are solid. The motor alignment is slow, very slow, and seems counter-intuitive in its deployment at times, slewing through 200 plus degrees of sky when slewing the other direction would make so much more sense. Setup  becomes quicker with practice and alignment comes pretty close to the selected object. Fine control of centering is tricky, too. But, for the money, its a good deal.
877530
The wide angle lens is good for what it is on my iPhone5s but the fish lens is subpar. The quality isn't that great, probably 5/10.
3421116
This is a VG lens, and a good value if purchased used.  It's a bit heavy but that's from the 2.8 ability.  The lens hood notching to fit to the lens body needs a little work in the design.  It does not always go on correctly and it is possible to put it back on the lens reversed and to miss fitting the notch/threads correctly.  There is strong vignetting apparent from 2.8.  If you are shooting in high contrast and open sky, you will see the vignetting all the way from 2.8 to 5.6.  That's a little disappointing but it's not visible/apparent below 2.8 unless you really look for it.  If I am going to walk around with this lens I zoom it back in to 24mm.  The reason for this is that fully extended the lenses internals do make a slight noise as you walk, like some parts of the lens are pressing against the internals.  This lens is pretty sharp for a zoom.  Clearly a solid deal/alternative if you don't want to pay the high price of the Nikon equivelant.
3227612
Good price but I am experiencing a lot of fringing around the edges and especially in the corners. There is also a substantial barrel distortion that I have to later correct in post-processing. I am kind of sorry I bought it, but it's OK for non-important shooting on vacations, etc.
2450411
It is not well sensed on the screen. It is worth for the price.
4042623
This lens has been fun to use.  Although I am not a big fan of the fish eye effect, I bought this one primarily for it's ability to provide a very wide angle for landscape and scenery photos.  If the distance to the nearest subjects included in the shot is great enough the fish eye effect is not as noticeable.  The angle is indeed very wide.  Comparing shots made with this lens to another lens which also will adjust to 12mm the angle of view, the width, of this one is considerably wider.  Of course the two lens, both being 12mm will have the same magnification.  The non-fish eye lens just does not have the same width.

The picture quality is very good.  Lens flare is pretty well controlled so shooting in situations where the sun is not in an ideal spot does not result in flare such as I encounter with the other lens which can shoot at 12mm.

The fact that the lens is all manual is not a problem at all for as has been stated for focus, just keep it on Infinity and it's good to go.  And that introduces my main gripe.  During normal handling, the focus ring never seems to want to stay at Infinity.  I know, it's just my handling of the lens during shooting and it's something one can just be careful about, but I find it moved to a much closer focus distance quite often and I'm never sure just how it got moved.  I think just more practice with the lens and I'll be less prone to accidentally rotate the focus ring.  Or perhaps a small piece of tape added could hold it in place.

The lens does not have any electronic communication with the camera.  Again, not a problem for me.  Most often I set the aperture to f/8 and adjust the exposure just like I do with any other lens.  The shutter speed.  That's manual operation and that's all I shoot anyhow.  For those not wishing manual operation, set it to Aperture Priority and let the camera adjust the exposure.  That works fine too,
2969170
build quality is good, optics are not  as good (read immersive) as the ones from Google Cardboard (i.e. you see a box in front of view rather than taking the whole field of view)
490873
I got this for my sony thinking it would be great to be able to reduce the amount of solar flare I get taking some shots. The lens I used was my kit lens 18-55mm. But when I zoom out for some wide angle shots I can see the hood in the corners of the shot causing vignetting, causing a difficult edit. I liked that it came with a cap and as long as I stick around 24(or so)-55mm I won't have that vignetting.
3768174
it was a good deal but the screen angle was kinda annoying.
once u fix it to the mount, it is fixed and there is no other way to change the angle of the screen.
i put rolled up paper underneath of it and it is not pretty.
but the resolution and color/ brightness meets my expectation
4652078
good starter screen the contrast is not so good and was really noticeable when I upgraded to a fixed frame screen
290757
It works but there is significant distortion at the edges
254252
The case is good. As so are the threading for the lenses.

The fish eye is a little fuzzy. I checked and cleaned the lenses and it's still not perfect.

The wide angle works well. It does add more to the side of the pictures taken. It's clear but I have noticed my focus keeps adjusting when not moved.

What you get for price. It's a good product.
516389
Got this instead of paying a premium for a B+W filter. The Promaster Wide CPL 77mm is a very good filter for the money. It does it's job well; takes the reflection away from water or glass effectively, and allows for those deep blue skies. However, a strange thing I noticed on the filter glass when cleaning it. I held it up to the light and notice streaks on the glass, like a few water droplets that had run slowly along the glass. These are apparently permanent, it looks like some of the coating was allowed to run and dried like that. Fortunately, it doesn't seem to effect the quality. Another con is that it sometimes produces light halos where sky meets and edge such as a horizon. Also the skies come out even across the frame. It's partially to do with the lens used, a Canon EF-S 10-22mm, which has the usual peripheral illumination problems, but I had half expected a 77mm filter to compensate for the color differences and corner darkness.