Great drinking buddy because: Jorah is another loyal drinking companion. Dude wouldn't just pick up your tab: he might take a bullet for you. He has a bit of a dark past, but who hasn't dabbled in the slave trade in their younger days? The important thing is that he has learned from his mistakes to become pretty dope.
Potential problems: He won't stop going on and on about Daenrys. It's never going to happen bro, get over it.