I have one on my daughter's nano. I originally put it on my wife's 30g cube, but it is WAY too "streamlined" in output for a tank that is more than about 10" front to back. Her tank is about 18" front to back, and there was basically a light "curtain" right in the middle with a dim front and dim back. It MAY have been acceptable with two of them, one behind the other, but by that point the money was out of scale IMO.
Plus, (again, IMO) there is no excuse for these lights to have a switch to change from blues/all, instead of two cords so it can be controlled.