This is the best party game in my opinion. I loved Rock Band 1 and now they have even made it better. The new instruments are a huge improvement from the 1st bundle everything about them is better. Almost all the songs from RB1 are able to be played on RB2, no it is not a free upgrade but it only cost like 5 bucks and it is well worth it. They release songs every week for download and the list of songs from RB1 & RB2 with the downloadable ones makes for endless fun and hrs of entertainment.
As for as changes go they have a lot more online stuff now like online band world tour, they have online duels, battle of the bands and more. It is like they really listened to the fans and everything you wanted or wish they had in RB1 is in RB2. I think the only thing missing is the making your own music like GH World Tour is going to have. They even added a no fail mode that is super cool to turn on at parties and stuff for those who want to get involved but suck at video games. lol
This game is loads of fun and if you like Guitar Hero and RB1 get this game.

this game is so much better than the first the songs are alot better alo the old downloads you got on one are also on rock band 2 i suggest playing this its great