I think the scene in which Vengeance closes on Enterprise in the warp "vortex" was quite literally breath taking. In so far as the design of the ship is concerned, I can't really claim that I like it, but I don't like the design of the HMS Rodney either, but you can't argue with the effectiveness of a ship that stands up to and dukes it out with the Bismarck!
Specifically, however, I find the cut out in the primary hull distasteful. What possible purpose does it serve? Not a ship I would have designed, but I am willing to suspend my disbelief, even considering her rather questionable size. (How rigid would a structure that large actually be?) Ever considered the Ju-87 Stuka? It was designed, at least in part, to instill terror in those witnessing it. Same principle could apply to Vengeance I suppose. (And before people jump on it, I'm not comparing Starfleet to the Nazi party! I'm comparing design purpose, not political philosophy.)
My biggest problem is with her "minimal crew" aspect. Warships carry large crews for a reason, you know. In battle it could rapidly become necessary to replace casualties at critical posts; damage control requires manpower reserves. But then JJ, despite having given us a new, vibrant take on Trek, obviously hasn't the first clue as to how a hierarchical organization such as the Navy or Coast Guard (or Merchant Marine for that matter) actually works. Though this is an issue, it doesn't keep me from thinking that Into Darkness is a phenomenal film.