@jws Shake on the iPhone is fine. Shake on the iPad makes my wrists hurt and triggers accidentally more often because I often put it down on my lap quite quickly and then pick it back up again, which can register as a shake.
Still, I never got the hang of gestures using more than 2 fingers. I can remember a load of emacs chords without problem, but gestures…not so easy. Things like zooming and rotating are obvious enough though.
/@matigo