actually, having now just downloaded this app, I can say, it's even better than it sounded when I first heard about it in this thread!
I agree this app is awesome. Unfortunately it appears to be confusing my home button function.
So I have it playing music, screen display off and the lock screen controls active. when I hit the home button to wake it up it starts to wake and then goes black. I have to hit it a second time before it wakes up.
Even after stopping music playing (pause it) the screen still wont wake up without hitting it twice. Also, I'm using LauncherPro (free) and have the home button set to pull down my notification bar... it takes multiple hits before it will work.
I killed the music player and restarted my phone and now things are working right again. This is the only app I've downloaded recently such that I've noticed a difference in the functioning of the home key.