It's never too late to turn things around– to make a clean break– to start over. It seems like that is a theme that runs through many a Ben Affleck movie.
You know he's up to no good with the company he keeps and the things he does when he's done with his day job; you know he loathes his father, and adores his dead mother; and you know that he's deceiving the one he claims to love. And yet you can't help but harbor the thought that this will all be behind him sooner or later, and that he'll turn over a new leaf. And that is exactly what he does.
The road to redemption might be a long one, but he gets on it, and you know that he means it when he says, "I'll see you again– either on this side or the other". Not an entirely believable script altogether, but the suspense, drama, and acting are a strong compensation for it.
And the Bostonian accents are impeccable all the way through. It's a lark, a shark, a walk in the park!