I’ll keep this brief … there is plenty to say about the finale, but it’s late, so I’ll stick to one particular point.
Boardwalk Empire is a very good series that doesn’t quite make it to the highest levels. Good as it is, for instance, it is not as good as Sons of Anarchy. But if you go back to my complaints about the recent Sons of Anarchy season finale, you’ll understand why I thought the Boardwalk finale was powerful, gutsy, and appropriate. Terence Winter didn’t flinch when it became obvious what had to be done. As he explained in an interview with Alan Sepinwall:
I'm really hoping to piss a lot of people off early in the hour who think this is phony and we're just trying to undo the situation we just spent 12 episodes creating. … [I]f you want to have a series that has some balls and really honest storytelling, then we've dug ourselves into a position where we pushed our main character into a corner and we really want this guy to come out as a gangster, then this [Jimmy’s death] is the only option. And anything short of that is phony and is cowardice on our part, because we're trying to preserve a situation that works better for us.
Winter knew that Jimmy’s death was the proper narrative move, even though it meant losing a character and an actor who will be missed. The comparison to Clay on Sons of Anarchy is pretty clear. Grade for Season Two: A-. Grade for season finale: A.