Fruit Ninja Kinect definitely doesn't live up to it's iPhone predecessor.
Unfortunately, the game isn't nearly as great as it should be.
I have to give the creators props, first. They did a great job of recreating the game on a bigger scale. But their job was too good. The Kinect version is exactly like the iPhone original. Fruit Ninja Kinect lacks something new that would draw players to chop and hack at virtual food.
Secondly, the game colors are great. In games I look for color schemes. Fruit Ninja doesn't really have a particular color scheme, but the colors are beautiful. If you're gonna play, play on an HDTV. It will improve the mediocre experience you're about to have.
And now we get to the bad stuff.
Really, there's only one thing that bugs me, and probably will bug you too - the entire fruit-cutting experience. The Kinect controls are... sketchy, to say the least. I found it hard, actually. This game is not enjoyable. The system requires large, hard movements of the arm to chop fruit. The iPhone game delivers a much more relaxed, easy, guaranteed way of scoring points.
I was to angry to even consider playing multiplayer.
If you're going to play this game, be warned. Don't waste your money on it. Hack away to your heart's content on your iPhone, and let the uninformed waste time sweating and trying to beat a score of 50.