Kameo has gorgeous graphics, and shows the 360 off to good effect. In the past I've called Russ over to see some new game with good graphics, and he's not too impressed. But, when he saw me playing Kameo he seemed quite impressed with the graphics of the game. Since he's quite the curmudgeon when it comes to games, this is high praise indeed.
The gameplay is smooth, and so far is reminiscent of a smaller-scale Zelda-style game. It's quite linear so far, and I agree with other reviews that criticized it's overly-difficult beginning being followed by a simple tutorial. After this odd choice in game flow, it improves, and I'm having a blast playing it.
I'll post more after a few more hours of time with it, but in the meantime I think it's safe to enthusiastically recommend this to those who like Zelda and/or platform-style games. It's also a strong introduction to what the 360 is capable of doing.