It’s forbidden to say lashon hara about a dead person, especially if he was a talmid chacham. No matter what he did, there doesn’t seem to be any to’eles in discussing it. If you want to find out what you should learn from him and what you shouldn’t, look in the Shulchan Aruch, or ask your rebbe. Let’s just be dan lekaf zechus, and assume that whatever choices/mistakes he made were done with good intentions, and the rest is none of anyone’s business. If you enjoy his music, fine. If you don’t, fine.
