[gekko]

You will be fine no matter what game you start with. HOPOs are improved as you go, and the HDTV lag issue isn't there anymore, but the game difficulty itself is pretty much identical.

I've heard GH was easier than GH2, but everyone who has played GH3 says it won't be much of a challenge to those who have mastered GH2. If you can beat all of expert on GH2, you have enough skill to be able to beat all the songs on GH3 after a few attempts. It's not like GH3 is designed only for people who have mastered the previous, it's at a similar difficulty, just with different songs.

But if you are just investing, I would say but GH3. It has the best guitar, and then just buy the stand-alones of the old ones.

But just a little word of advice, start on hard. You'll develop more bad habits than you can ever imagine playing easy and medium. It's not even worth it. Go hard, and never look back.