For a small tank, where you don't mind noise..I will say it does the job....for me on a 48g with low stocking level. With the 18 blade impeller upgrade. Nice dark skimmate and no adjustment.
However, I hear several nays. I have no basis of comparison. It was locally available, whereas I would have had to order a Remora, etc. from the US.
For the price it does a good job. I have the prizm and the Remora ...and i like the prizm a lot better. The Remora has never skimmed well for me...Just my .02
I hate mine on my 20 Gallon reef. I'm switching to a sump based one as soon as I finish my sump. It skims enough for the money you pay, but it leaves the top of the tank untouched (read: oily coating on top of water). I'd recommend getting something nicer for a hang-on if you can afford it. Like the CPR-Bak Pak II.