I have done my fair share of ketamine - fair being just that (only about 5 times) - and I'm heavily put off it in general, and try and steer people clear of it, due to it's abuse potential.
People who got unresolved problems seem to take it waaay too far and you can just see their character drain away when they sniff a line - vacant stares appear - it's just another easy escape from a temporarily shitty reality, much like alcohol, too much ganja, heroin, or any drug really.
Not physically addictive - I never found it had that pull.