If there were more songs on this I might bite, but 49 total tracks is a ridiculously small number for a full price game, especially when less than a fourth of those songs are ones that I'd actually want to play more than once, and there's no DLC coming to the rescue.
If they're going to price these "expansions" the same as the core games, they need to start shipping with the same amount of content:
Guitar Hero II - 74 songs
Rock Band - 58 songs (but saved by a shit-ton of DLC)
Guitar Hero III - 73 songs
Rock Band 2 - 84 songs
Guitar Hero: '80s Encore - 30 songs
Guitar Hero: Aerosmith - 41 songs
Guitar Hero: Metallica - 49 songs
Get that weak shit out of here or lower the price IMO.
If not, I'm perfectly content to wait it out until the market sends it down to the proper price level like what happened a few months after the other two "expansions" came out.

