If you liked this one then I'd suggest keeping an eye peeled for this other movie called
You're Gonna Miss Me:
http://youregonnamissme.com/
it's about Roky Erickson (of the 13th Floor Elevators and others), another "genius" musician who's mentally ill. The two guys' stories are actually pretty similar... I think both movies are good. Worth tracking down if you're not sad enough after Devil...