OSU!
The graphics, story, songs and gameplay are slightly better than Ouendan 1 and EBA and it's obvious the developers addressed the problems form Ouendan 1 (cut scenes can now be skipped, replays can be watched and the sound is less tinny than Ouendan 1).
There is alot of personality in Ouendan, from a little boy trying to get he likes to like him before she moves away to Saving the World from being frozen over; it always has this anime like feel.
If you have played Ouendan or EBA I highly recommend Ouendan 2 due to it's addictive nature.