Braved the storm to go see all 7:45 of this (two parts) yesterday. I'm a bad critic, but it's a good play, and one which will stick around forever, revival after revival. Nathan Lane is a bit of an odd choice for Roy Cohn, though he's very good, and Andrew Garfield is quite good as Prior.
I first saw it back in 1996 or so, in Providence, directed by one of the men (Oskar Eustis) who had originally commissioned it. That production conveyed a sense of urgency, particularly in the first part, a sense of powerful unsettlement, more than this one, though this was better (and more expensively produced, obviously) in other ways. One of those theater productions I still think remember 20 years later.
Worth seeing if you're near it.