Even though the problem still exists in iOS 6, I think I have found a work around:
In the Piano, tap the last button just above the keyboard.
In the window that opens, called Keyboard, turn On the Velocity control.
This will show the velocity control on the left side of the screen over the keyboard. This control seems to be used to set the maximum and minimum volumes of the keys according to how hard you hit the key; so just bring the minimum volume up to minimise this range.
In the Drums, at the top of the screen, tap the 3rd button from the right to open a window that has an option to set the Velocity sensitivity. I've noticed that High sensitivity, or No sensitivity seems to work OK.
Hope it helps.
I am discovering this acceleration problem exists in more apps than just GB.
Games and other velocity sensitive apps are not responding as they used to before the iOS 6 update.
Now this is a real issue that needs to be addressed and in doing so, may resolve the GB issue if they can correct the touch screen loop programming.
I'm not in favor of workarounds, they don't address the issue correctly, and this problem is becoming a real nuisance.
This issue should be high on the programmers to do list.
I will submit a suggestion.
I agree. I am seeing a number of apps that just don't respond when tapping on the surface of my ipad 3.
A previous commentor mentioned that since this is a user to user community we should make sure to give feedback to Apple by using the following link:
"Then make sure, that Apple hears you and use the feedback form below - the more, the merrier:"
Thanks for trying to get this fixed.