My new four year old OTTB is pratically bombproof, sooooo laid back, rather slow, and already jumping full courses (and winning).
Before she hurt her back, my trainer took in promising OTTB, trained and sold them. Although a few were a bit whacky, most are just AMAZING! My parents lease an OTTB from my trainer. He's really sweet, and jumps courses with my mom, who's a bit nervous and not a begginner, but not a great rider.
I think they get a bad rap, or they go to people who don't know how to train them. My opinion is that with a knowledgeable and patient owner 80%+ OTTB are great horses with power, ability, and heart for many different disciplines