Bought it this morning for Wii.
Its pretty damn awsome, shits over the others. Songs are all alot better, and some cool new features aswell.
Players of GH2 would know that u get to do encores after u complete 3 songs in career mode, you get to do this aswell in GH3 but some other times u get challenged by real guitarists such as Slash and the dude from Rage Agaisnt the Machine (cant remember his name haha).

Anouther thing i noticed is the dificuilty of the songs has been raised which is good, i can play on Hard but only just, so i ussually just play on medium.
I got up to the boss level before and fuck its hard, its a battle between you and this devil dude. One thing with battles aswell is that when u hit some notes u get these 'weapons', when u tilt ur guitar it affects them and makes them miss notes. Thing is though in the boss, ive tryed it 3 times now and failed each time because i never got any weapons, yet the devil is always getting weapons and making u miss.
I put up a video to show how much i suck and how the battle format works
Vid will be up soon