It's okay - pretty bright. Read the rest.
923455
You can only attach this once the umbrella is up. You cannot leave it in place. There is interference with the umbrella spokes.
1665015
It's quite bright, especially for LEDs. It projects a pretty cool pattern of red, green, and blue. It does NOT cycle the colors, nor is it responsive to music. You turn it on, it lights up and spins. Simple. The workmanship is not bad but not great. 3 of 6 of the ones I ordered kind of 'stick' for a second on each rotation. The other 3 are smooth. I have not tried to fix this yet, the plastic dome is simply screwed onto a metal spinning post with a screw, so it may not be too difficult to fix- maybe a sharp edge of plastic, some glue, possibly a stripped gear, or something else may be causing the problem. But the colors are extremely vivid being LEDs, and I'd say it projects well over 180 degrees, possibly 270 degrees. It's visible across a somewhat sunny room. And it looks cooler with a fog machine.
Overall, it was around $6 and they all work reasonably well. You really can't go wrong with these for the price. I can't wait to use them with my Christmas display.
4192440
It works.  The screw holds it securely in place.  So far, so good, but the LED that tells you it is working is really bright.  I wanted to use this to charge a couple of iphones in the bedroom at night, but the glow is just too much.  I guess I could tape over the LED, but wifey says that would be too ghetto.  So it's back to the drawing board.  I guess I'll use this one as an outlet multiplier in the garage.
4471686
nice, it's a bright LED light not warm.  Not that they advertise it as warm, but just letting you know.  :)
1678803
works as advertised. Bright but not very bright.
3327562
Yes, I like the flashlight.  My only real issue, and this is perhaps more my fault, because I did not read the specs as well as I should have.  I doubt it actually produces 1200 lumens, but it is a very bright, white light.  very bright and very white.  It can be a bit of a pain, literally, when sometimes all you need is a little extra light and when you press the button you are blinded by a force that feels like a second Sun.

Now, if you carry this because you have to walk in a dark area and perhaps do not feel totally safe, then this may be the flashlight for you
3118468
The light is really, REALLY bright.  I find it impractical to use at night with another person trying to sleep next to me because it lights up the whole room.  That's fine if that's what you're going for, but it's just too bright for me.
1945215
If you just a need a fairly bright light somewhere and don't have the option of wiring up a light this will work great. It is not the most aesthetically pleasing but it works.
4731834
It's a little bright, but does what it is supposed to. I don't leave it on for long intervals though.  Don't want to hurt my little fish eyes.  Seems to get quite warm too.
1723356
It fits just fine & the color is bright white. The light output could be a bit brighter which is why one star get knocked off.
1657569
It is a nice light.  Don't know what the lumens are but its bright enough.  Tail light is okay as well.  Since I live in a city and park my bike outside I need to remove the light when I park the bike. The holder system is a little awkward; it takes getting used to.  Better than other mounting systems which invariably, for me, break.
685890
Very bright, good for those who need extra lighting
412857
The light is o.k.  It's not the brightest light, but works o.k.  I don't know if I would buy it again.  I use it to light up my drive way on the side of my house.
3145914
It's way too bright for me and it is a spot light, not flood. The plastic hinge designed to hold the light to the backcover and tilt it seems a little flimsy. Will see how long it lasts. Overall, for the price, it's OK.
3926912
The light is bright and has several options for flashing or steady use. I don't love the way it is mounted to the seatpost, though I've seen a lot worse. I cannot speak to the length of charge at this point, other than it is at least an hour and 30 minutes on low flashing mode.
1577389
I like it. It's very bright, which pleases me and annoys my wife. It works well. Nothing to complain about, for me.
1413102
It throws a nice beam with the 3 LED's.  I have it set to hit the ground about 10 feet in front.  Fine for short commutes.  The diffuser lens throws some light to the sides, which helps make you more visible (that's generally a good thing).  However, the diffuser also throws some light upwards.  I blocked that with some tape, otherwise, the glare would ruin my night vision; hence, 4 stars.

For my needs, this is a fine light.  My commute is fairly short, and I don't go very fast, so I don't need an ultrapowerful beam.