I'm currently a student at UConn so I've been ecstatic to see DB get drafted by the Pats and have had the pleasure of watching him play college ball. I think he'll be brought in right away in nickel packages and I could see him starting at CB by midseason. His athleticism and cover skills will allow him to get reps right away, he'll fit right in once he learns the system. If he can put on some weight and improve his tackling he has the potential to be scary good.
He's really a "do it all" type of player, exactly what fits BB's system and I really like the Troy Brown comparison. I could see him returning kicks this year, the kid is lethal in open space.
As for offense, I wouldn't look into that too far. Butler caught 8 passes last year in an abysmal one dimensional offense that was desperate for a playmaker in addition to Donald Brown. He's one of those kids that you just want to get the ball and give him room to make a play but I can't see that translating to the NFL game since he won't be able to get away on speed and athleticism alone...although it would be fun to see BB bring him in for some trick plays . But this kid is a hell of a player, an absolute steal at #41 and I think he will make Pats fans very happy.