Yahoo! Tech writer Christopher Null listed Rock Band 2 among his personal eight best tech products of 2008.
In the short write up he says that he finds it "humbling that I listen to more music while playing Rock Band than I do on my iPod". The game's biggest draw, it seems, to Null is its ever expanding set list and diverse music selection.
Makes sense, that's probably why music games are having such an impact on music sales.