If you're finding you have hand cramps, try a different control style. I personally found that Freakish worked well for me, using the left thumbstick to move between tracks, and the Left and Right triggers to hit the notes. The triggers are a slight bit slower than the bumpers, but I feel that my grip is better when hitting the triggers. I had little difficulty keeping up with the faster songs, though we'll see how it goes after a few more days.
I totally love it, played like 12hrs since release. After getting the powerups I started to fear that I won't have anything left to do, but those Gold Stars are really tough on some songs (unfortunately on the Blitz ones). I have RB1 export, where I goldstarred like 6 songs in a row, so those are a bit too easy, but yeah, the game is fine
I like it a lot. At first I was not sold. But after playing for a few hours It really grew on my. Not big on the competing though. And since I have a buttload of DLC (some of which I have never played in RB) I will be busy with it for a long time.