I decided to pick it up as well. Got through 27 of 42 on Hard.
I like the new wireless guitar. Got the Best Buy deal with the free Sex Pistols faceplate.
The seems that the game is a little more forgiving this time around when it comes to scoring. For example, there was a song that I got 93% on but still got a 5-star rating? Must've hit star power just right or something.
It looks like there's 5 characters to unlock in the Store. I've figure out 4 of the 5, but haven't figured out the last one yet. Must be another boss battle somewhere down the road.
The stars on Guitar Hero are based around your total score, not so much the note percentage you get. If you could find a way to hit 100,000 points but only hit 75% of the notes, you could get 5 stars. And you are right, there is one more battle before the end, but I'm going to save it as a surprise because it is really well done.
I beat GH3 on hard last night. I 5 starred most of the songs, but I played yesterday morning and only three starred a bunch of the songs in the 3rd to last tier. I just can't play it in the morning. Oddly enough, on the last set of songs Raining Blood is the first song you are supposed to play and that is the only one out of the group that I had trouble with. It is retardedly hard.