Brian was depressed & wasted at R & R Circus - early on - say the debut - he was terrific, - other highlights just off the top of my head, "It's All Over Now" & the chess sessions generally, the slide on "I'm Moving On,' 'Empty Heart,' 'Grown Up Wrong," etc - by Aftermath he was already losing interest in guitar, but on Buttons/Flowers/Satanic he made up for it with his contributions on other instruments (I esp. dig the theremin on 'Please Go Home' Mona psychedelicized), & the weird addition of mellotron on 'Stray Cat' (B
is odd & effective too.