I have the 36" unit on my 72" 125g tank and love it. I also have a DIY in-hood setup on my 48" 55g and like it just as much. My only complaint about the Marineland unit is that the daylight and nightlight setups run on a single switch and power supply so you can't automate them (or use external switches, which is what I do). But for the price-point they're hard to beat.
One caveat - if you're looking for a very bright light on a very dark tank this may not suit your tastes. Well, two caveats - I'm not sure if it's suitable for planted tanks (other than low-tech planted tanks).
But from me it receives a thumbs up!