There is a lengthy post on reefcentral about these units. I guess in the past they were on a magnetic ballast and weren't outputting as much wattage as they were claiming, but since they started shipping with electronic ballasts people seem to be happy with them and kill-o-watt tests have shown they are outputting what is claimed. The reflectors arent the best, but the unit overall is pretty good IMO, especially when you consider the price. I have one which is FS now (cant use it anymore since I added a canopy), and I was able to keep all SPS (even in bottom 1/3rd of the tank), and anything else I wanted.
Are they the best units? No. I wouldnt hesitate to buy another if I have another open top tank in the future though.
edit: I will say the stock bulbs are pretty crappy, plan on changing those right away.