This is extremely awesome news. The fully backwards/forward compatible DLC makes this game that much better. Now I just need to decide whether to buy the bundle or just the game disc. I suppose I'll have to see just how improved the instruments actually are first.
While it kinda sucks that PS3 owners get shafted on RB2 for a couple of months look at it this way. At least you'll be able to read 360 owners experiences with the game and new instruments before deciding on whether to buy the bundle or just the RB2 game disc. And hell, at least you're not a Wii owner.
