Kinect Adventures is a fun, if limited, introduction to the Kinect's capabilities.
Rally ball was really cool at first as the Kinect's controls work perfectly for a game about smacking a ball back and forth. But my biggest disappointment with rally ball was that there was a considerable lag for leg movements, which meant I either had to crouch to hit ground balls with my hands, or miss them.
One of my other main gripes is that a lot of the games, like rally ball are played from a view directly behind the translucent avatar. Yes, you can see through their bodies, but they do block some of the play area, and are very distracting. It would have worked much better just to see a foot or hand displayed on the screen.
All in all, these games are a fun introduction to the Kinect. Yeah they're pretty limited, but what do you expect from a compilation of mini games that you get with the bundle?