I haven't personally tried piracetam, but erowid has a good section on piracetam and other nootropics. It generally seemed from Erowid that nobody had any bad experiences unless they were also on hard drugs.

Piracetem:http://www.erowid.org/smarts/piracetam

Nootropic Vault:http://www.erowid.org/smarts/smarts.shtml