Guitar Hero 5 is the new installment of the old favorite series, should you buy it? Depends on your musical preference.
The whole game comes down to the track listing. If you are a fan of the music that is in the game then you may enjoy it, if you are a fan of shredding in the Guitar Hero games...pass on this. With the introduction of the band feature in Guitar Hero: World Tour, the guitar parts became simpler overall due to the need of finding more well rounded songs that support vocals and drums. If this were strictly a guitar only game, I wouldn't even pick it up as the songs are tame and fairly simple to play.
As it isn't, it is at least worth a rent. The songs that lack a difficult guitar part often have difficult vocals or drums to back it up. Still, the songs don't take as much effort to beat on the hard or expert setting (this is coming from someone who could barely beat GH3 on hard).
Overall the game is solid, not the best in the series but a solid improvement from the previous entry in the series. If you are a Guitar Hero fan, this game is worth the purchase because it comes with a mail in offer for a free copy of Guitar Hero: Van Halen, you are essentially getting 130 songs for 60$.