One could pick apart the Sima SL-20LX over a number of what I consider small points. The battery can't be replaced by the user. The unit will not function as a light while being charged. The light pattern is definitely hot at about five feet or so and will overexpose your subject if you don't compensate. They should provide a clip-on diffuser: the light is very bright and will bother people looking straight at the camera.
All those "negatives" and I stil give it 5 stars.
Why?
Because this much light in such a small package at such a low price is on the order of a miracle, that's why.
Even though the close-in light pattern is hot, once you move six or more feet away from your subject, you have a nice blanket of cool white light that renders color well. It is good out to almost 20 feet.
A 2.5 to 3 hour charge gets you about 1 hour of light. It would nice if you could adjust the output power with a switch, but you can't.
At the price, you can afford to carry a couple or more of the units with you if you need mroe than an hour of light. A unique and welcome feature incorporates hot shoe mounts on three sides of the unit so you can build your own light arrays by connecting one unit with another. Very clever idea.
Sima includes a bracket with a tripod screw and a hot shoe adapter. One of the units I tried the SL-20LX wqith is a digital camera with video capability. The video, within the limitations described above, was gorgeous.
So even though some people might find shortcoming in this unit, I see it as a wonder of the age: a small, powerful, highly portable light source at an affordable price. That truly merits 5 stars in my opinion.
Jerry