hey there mate,
I bought one of those, but the blue and red mixed one, and to be honest, It doesn't seem to put out much light at all, so I didn't even bother using it, although I'm gonna try it over a few seedlings to see how it goes with them, I would say it's probably best as a supplemental lighting rather than your main light source, you'd probably be better off buying a big CFL.
Although I am a noob, as I say never actually used it, so if anyone else has tried one and thinks otherwise, maybe you can help this guy out?