As far as side-scrollers go, and puzzles in general go, on Xbox live arcade this is arguably one of the most valuable. At 800 points it's still probably not worth the price, but in comparison to the majority of Xbox arcade games, this one is probably the most worthy of the price tag.
If you're into puzzles and you've never played the PC version of N, this one is a must buy. If you can at least download the demo or try out the flash version on the PC then do that first, because this game is a well designed, quick thinking, highly addictive, open, and enjoyable puzzle experience which no one should be left out on.
Gameplay - 8.5
Graphics - 7.5
Sound - 7.5
Longevity - 9