I was hoping this would work for playing electric guitar in classical position. Unfortunately, the electric's thinner body isn't stable on the cushion, so I ended up gripping the guitar more firmly to keep it in place. The cushion moves around on my leg and the guitar squeaks when in scoots around on the cushion. All in all just really bad for my posture and for my playing.
Judging by the other reviews, it's probably great for classical guitar, but don't expect it to work for electric.