Would be a great pick up. If, and it's a big if, he's somewhat healthy and would come for what the Celtics could pay it would be crazy not to sign him.
As far as his personality. Never heard a report that team mates didn't like him. Sure he can be a jerk on the court, but if you haven't noticed, so is Smart. Get's a lot of bad T's. Argues with refs, Goes at it with other players. Yet for some reason fans here love him.
Cousins is one of those guys that you hate, unless he's on your team.
Kind of like the Patriots.