Brilliant game - while it may get difficult later on you'll find yourself spending hours playing.
This game has a great track-list and with download-able content it just gets better with the likes of Muse and Velvet Revolver packs available to download.
As good as the single player is - the most fun can be found in Multiplayer. going head to head in Pro Faceoff can provide hours of entertainment at a time, bring in a group of friends and take turns and you'll wonder what happened to the time.
A few more minor things I dislike about this title: Battle mode is all about luck, and if you're on a higher difficulty against someone on a lower difficulty you'll have a much harder time winning to the point where a newbie can pick up the game on easy and most likely beat you playing on Expert. The Guitar Controller starts to "break" after a short while, while there are numerous fixes for some of the problems they shouldn't be there in the first place and why does the controller come in two parts anyway? The Box is the same size as that of the Guitar Hero 2 box!
Overall is this a very solid game and despite it's very flaws here and there you'll find yourself coming back to it over and over again.