I have both games and both are good (and unfortunately- Rock Revolution...which is NOT good), but I actually prefer the guitar in Rock Band 2 for a few reasons. It's nicer looking, "bigger, but thinner," and it doesn't have "separated frets" (which I HATE). But that is purely opinion and personal preference.
Drums don't matter to me because I have the Ion Drum Set ordered.
As far as the actual game...I definitely like Rock Band 2 better. I currently have around 400 songs for it and believe me....some damn good ones. If downloading isn't an option for you, then song selection may be a toss up. I'm loving the Motley Crue, Nirvana, and ACDC albums. And one of my favorites by far is Simple Man by Lynard Skynard and Behind Blue Eyes by The Who. Once again, just preference.
As far as gameplay, they are really similar (obviously), but I do enjoy the Rock Band 2 look and play better--which may be just because I've played it many more hours. But one amazing addition to Rock Band 2 is that it has a (Career Mode) Challenge Mode that ties directly into your downloadable content. For example, you may "unlock" new challenges to play once you download the Nirvana album....as you continue to download, you realize that the single player career mode will never "end" because it is being continuously altered to use your downloadable content. This really extends the game for you.
One other factor to take into account is the platform you are playing on. I am playing it on my ps3 instead of my 360 mainly for song sharing with my buddies on downloadable content....but besides that, if you are playing it on a ps3, Rock Band 2 has Trophies and GH:WT doesn't. I love my Acheivements and Trophies so this was a huge added bonus for me.
Anyhow, just my two cents. Both are similar games and I'm sure you'll enjoy both.
PSN ID: Sorrow880
Gamertag: Sorrow80
Wii #: 8132 1076 3416 7450
