I have tried all three betas on my iPhone 4 (before selling it), my new iPad, and most recently beta 3 on my new 4S.
I still find 5.1.1 to be 'zippier' than 6.0 on the 4S, and the gestures on the iPad (pinch to return to home screen) have stuttering animations at times. So, for me, it's not (obviously, it's beta software) primed for day to day use.
I'm back on 5.1.1 on both devices, and will remain so until the public iOS 6 release.