I am one of the few people who love this game.
Good- Outrageously fun. Turned out the best it possibly could (Peripheral). Good graphics. Amazing song choice.
Bad- Not enough songs. Wrist may be sore. Too short. Too easy even on expert. Grainy sound quality. Not too mobile..
The peripheral seems fine and comfortable, until you take it off. Then your wrist hurts. So it hurts after you play. The game only has 25 songs (plus the bonus song) and the game is easy to beat. However it took me a while to unlock everything. This song could not have picked better songs. I knew all of them. I have downloaded almost every song.
If you have a DS and want GH. Get this!