A few times I've had to move stuff out of the way because it would trigger a false hand presence.
Lighting hasn't been an issue for me; I get assorted warning messages ("Bright light!" "Low light!") but it doesn't seem to make a noticeable difference in what I've been doing.
I tried shining a laser pointer on but it didn't do anything. That was disappointing. :)
My understanding of it is that it uses near-infrared LEDs (slightly longer wavelength than visible light) to illuminate your hands, and that's why certain types of light sources that emit a lot of light at these wavelengths are alleged to cause trouble. It makes sense that a laser pointer wouldn't cause any interference because laser light is not in the passband that the cameras can see.
My experience is that in a moderately-lit situation (or a low-lit one) the thing works pretty great.