If you've played the first game, you know what to expect. They also added the ability for 2 people to dance at once, which is an awesome addition for parties. The voice control works great, and helps a lot to find songs and simplifies the Break It Down mode as well. It's nice to be able to repeatedly practice moves by skipping around.
The game picks up your movements quite well, and you can actually somewhat learn how to dance from this game. It's just great fun to do. They could use more variety of songs aside from all the hip-hop music however, so DLC of more varied genres would be nice. (Country/techno/latin/or even more danceable rock songs would be cool.)
Another criticism is in song selection. It is just way too hard to quickly preview and pick the exact song you want using Kinect motions. Navigating the list takes forever, and once you do find the song you want, it's easy to skip past it and/or pick the song above or below it.
The controls are way too touchy, so I believe there needs to be a different interface altogether. Maybe have 6 blocks on the screen at once showing the 6 songs you can choose, a swipe takes you to the next 6, moving your hand over a song for a second or two begins its preview, for example. Something... anything would be better, to be honest. I found myself using either the controller, or voice, just because song selection was ticking me off.
These are pretty minor issues, however, because I LOVE the game overall, and will be buying the 3rd installment as well. The whole import of tracks like Rock Band is a huge win, and makes me love Harmonix even more.