I wasn't that thrilled on the first pass, don't care for 80's songs either, but some of the songs have definately grown on me. I think that the GH franchise has such high standards that expectations for the expansion were too high.
The only things that really irk me:
* "the warrior" - fading out at the end
* "what I like about you" - everything about it, always hated that song
* Setlist skewed on the easy side - I'd love to have seen all of tier 1 removed and then replaced with a "harder" tier after Play With Me.
All in all, I think it's a nice bite-sized snack until GH3 and RB come out. (because lordy knows if GH2 DLC is coming)