What is the sustainiac like?
If you strum a chord, does the chord keep playing like it was a keyboard, or does the sound change into harmonics and feedback? IOW, is it similar to standing next to a speaker?
Does it work with clean tones as well as gain?
And how long does the battery last when using it?
Well, it works on any sound, clean or with distortion- it creates a feedback loop. Usually a switch will switch between the fundamental sustaining or a 5th above. If you've ever gotten feedback from an acoustic, where the strings start ringing and don't stop...that's the sound. It is very musical, actually, and guitarists like Adrian Belew and Robert Fripp use it a lot. No idea how long the battery lasts.