I was waiting a LONG time just for this demo and I finally got it ( October 9th ). Here is my review for the songs.
Shout At The Devil: 4/5 A good song by Motley Crue, but it's pretty easy even on expert.
You Really Got Me: 3.5/5 Of all Van Halen songs, why this one? It's good, but there are better.
Strutter: 4.5/5 Catchy song by Kiss. Definitely one worth playing.
YYZ: 4.5/5 A great lyric-less song by Rush. Probably the best of the four.
The four songs on the demo isn't much, but it is enough to hold you over until the game is released.
Also, the Guitar Hero 2 song list has just been confirmed.