Better than the original for a lot of reasons (read full review)
Graphics: Slightly better
Sound: New songs
New things: New guitars, skins, characters, costumes for characters, songs such as laid to rest, madhouse, beast and the harlot, six and thunderhorse. Multiplayer is a lot better. When you do 4/5 songs in a list you'll be asked to do an encore as the last song of the list and you can get sponsored, everything you buy is shared between each difficulty unlike the first game where you have to buy everything in each difficulty. The special guitars are pretty sweet.
Value: A must buy if you like this game