Thought it was decent. Looked about as realistic as you can really do, for a sub. Rooms were roughly right, although too big. TV problem, though, imagine it would film like shit in the tight spaces that are really there.
Couple other minor nitpicks (I work with subs for a living):
-They picked a number that belongs to an attack sub, and called it a boomer. For the story, it has to be a boomer, but 753 is the Albany, a LA-class sub. Look was right for a SSBN, just should have picked an imaginary number if they weren't going to intentionally pick an active one. Colorado was a fine pick, keeping with the state names for BNs. Anything 744 for 749 would have been smarter picks, as they immediately follow the SSBN numbers, and are unassigned. Starting with 750, they go back to attack boats, the 688-i class.
-They picked the Illinois as the attack sub used to shoot at them at the beginning. Probably a good call at the time, as again, name sounds appropriate, but not an active boat. Except that in the interim since they wrote/filmed it, that name has been assigned. It's going to be the 786, a Virginia class boat. (I work on those). Not their fault, just bad luck. Not too bad, I guess, as the show will be over one way or the other long before it becomes an active submarine, just coincidence.
-As mentioned, Cobb isn't the guy's name. Chief of the Boat, COB. The LT said it all out the first time she addressed him, and then just called him COB after that.
Other than that, thought it was pretty good, detail-wise. Nothing's going to be perfect (oddly, one of the Stargate tv movies (continuum?) was about as close as I've seen) but the look was about right for most of the stuff in/around the boat. Conceits to tv, but equipment mostly looked right.