First, as the picture may suggest, this bulb ...
357223
First, as the picture may suggest, this bulb is much longer than the halogen it replaces.  Second, it only lasted about two months before going dim and then dying.  Not worth it.
1875351
Okay, clearly one of the most important things about LED bulbs is whether or not they really do last as long as they say, but it will hopefully be years before I feel ready to comment on that.

What I can say is, I really like the light this puts off. 1000x times better than CFLs.

The problem is, other than testing it, I haven't really been able to use it, because I got it for next to the bed, and it doesn't fit into that lamp. The problem is how much wider it is just above the base than the base itself -- for a flared fixture (I don't know if that's the right word), it doesn't fit all the way down in, and so, well, the light doesn't light up! Pretty big flaw.

So, I would recommend making sure there's some extra space for the overage, but as long as you can use it, at this point I do recommend this bulb!
603988
The bulb is projecting a blue hue on the right side of my screen.  Messes up the quality of the picture.
4021396
It's just a LED  replacement bulb in there. Save your money and just buy the bulb.
2438007
This bulb arrived on time and works as it should.
3002754
It's just OK. The first thing I noticed is the "prongs" are flimsy little wires that bend and move easily. I ordered 2 pairs ( one for each back-up light and one for the center stop light). The very first bulb that I installed failed ! I was pissed. Fortunately, the second and third ones worked. I haven't installed the forth one...luckily, I have a spare. The second thing I noticed is the light does not spread out like the original OEM bulb. This bulb is more like a spotlight. I'll have to actually test the bulbs at night to see how well the light spreads out to determine if they do a better job of illuminating.
2317755
Total length of item too long; bulb protrudes from its installed position; supposed to be flush -- it is not
1598545
The good news is that the bulb (PAR38 Bright White) fit the fixture and works so far. The bad news is that the product description doesn't match the package and is lacking key information. First, the description says it is a flood and replacement for a 120W bulb. The package says it is a spot and replacement for a 90W bulb. The other missing information is that the package also states the bulb is not for use in totally enclosed fixtures and must be used in a base-up position. This is important information to include in the description, especially since it touts the bulb can be used for landscape and security fixtures. My landscape fixture is both enclosed and base-down. It isn't worth returning a $20 bulb, so I'll see how the bulb performs and how long it lasts.
4653680
I installed this on a tuesday, the picture was noticeably, but only slightly, less bright than with the original bulb.  It worked fine Tuesday  and Wednesday, but by Thursday the brightness had decreased further, to the point where it was no longer acceptable.  On Friday the TV would not turn on at all, with the pattern of flashing lights on the TV indicating that the bulb was again blown.  Amazon quickly refunded my money and I returned the bulb but I chose to order a replacement elsewhere, twice the price but I decided to go with an original part second time around.
3880752
This bulb is large, and the detail pops even moreso in person!
3835427
I actually bought this bulb at a local Autozone store. First of all, they are very expensive. 10 bucks for just one bulb. They would flicker most of the time. If you move it a little, it would start to flicker on and off. It seems to only flicker when I put it in the license plate light or the trunk light. It doesn't really flicker as much, or not at all when I put it in the interior lights. Also the color of the bulb varies depending on where you look at on the cap of the bulb. On the very top center of the bulb, the color is white with a hint of blue. But on the side of the bulb, the color is more white and yellowish. In the picture you can see that in some part, the light is yellow and green and in some part, the light is white with blue tint. These bulb doesn't worth the money.
831267
No problem screwing the bulb into the socket. The first bulb I tried works fine.
3701063
This bulb has an appropriate white light output and is of the same size as the prior light. Needed to return a previous purchase because the bulb was larger and didn't fit with the glass safety enclosure.  I gave it 4 stars because I am not able to assess its longevity.  If it lasts then it would receive 5 stars.
1097521
It is a bare bulb going into a MR16 base.
Very simple.
There is a clip to hold the bulb, which is very stiff. Be sure to insert the bulb before attaching to the track.
It does work.
818442
As soon as this was installed on TV it said bulb is near end of life and needs to be replaced.  I will purchase one from someone else!
4046428
I purchased two of these bulbs for an antique lamp that came from my parents home.  One of the bulbs worked just fine, but the second one only works on one wattage setting.  I did not return it, preferring to have an extra on hand in case the one in use burns out.  Sometimes the contacts on an old lamp just do not match up properly with the contacts on a new bulb. Possibly a good handy person can fix that issue with a little bending in the right places.  I haven't tried this yet, but will when the working bulb burns out, which could be years.  The previous bulb was at least ten years old!  Maybe the manufacturer could add just a smidgen more material at the contact points.
1173167
litterally. . . and then there was light.  . .the bulb that was on my microscope was functional. . (and expensive). . this change should have been done years ago!