I don't own guitar hero 2 but I have played it a lot. Its the practically the same game with different songs. You should look at the songlist and then decide. If you got bored of playing the game, then don't buy 3. If you got bored of the songs then get 3. Also the songs are harder and overall its more fun. If you have xbox its so much fun to battle your friends.
I won the NS signature contest and all I got was this lousy signature