The best band based Guitar Hero, the songs are killer, and while the non Metallica songs may seem out of place at first, you will realize these are mainly the songs that Metallica covered for Garage Inc.
My first Rhythm Game and I'm a huge Aerosmith fan so I am biased but it's overall a great time, and I do personally prefer it to Guitar Hero 3, though keep in mind it is essentially Guitar Hero 3 but with Aerosmith.