I give the movie a C-. I liked STID better than ST09, but to put that in context I absolutely loathed ST09.
Background here: I've been a Trek fan since I first discovered TOS in syndication as a kid. A lot of this thread has batted around the question of "what does it mean to say something is 'real' Star Trek?" Aside from the obvious but trivial intellectual property sense (i.e., if Paramount brands it as Trek, it's Trek), that's an unavoidably subjective question. To me, real Trek is the original series and the TOS movies. Everything else is a spin-off, and although I've enjoyed some of those spin-offs to various degrees, the TOS characters and concepts are the heart and soul of Star Trek.
So when JJA gave us a dumbed-down, hyperkinetic knock-off of those characters and concepts in ST09, well, suffice it to say I was disappointed. Some of the acting was good (Karl Urban in particular really evoked his antecedent, as everyone seems to agree), and the effects were good (but that's par for the course with a big Hollywood budget and CGI), but everything else about it aggressively insulted my intelligence.
By comparison, when I left STID, my main impression was "that felt almost like a real Star Trek story, except stupider."
In the discussions here I've read some really thoughtful criticisms, from Lapis Exilis and ConRefit79 among others; and I've also seen some surprisingly stubborn resistance to criticism and a lot of defenses along the lines of "this is what Trek is now, this is what it takes to make a movie succeed, so if you don't like it you're just out of step." I don't buy that.
I went in with pretty low expectations, and from the start the picture lived down to them, with the whole Nibiru sequence that piled aggressive stupidities and unanswered questions one atop another. (Why did the ship need to be underwater? How did they get it there without being seen in the first place, and how were they planning to leave? Why did any crewmembers need to infiltrate the locals in person? If someone had to do that, why the captain and doctor? If the nuEnterprise is as huge as it's purportedly supposed to be, how the heck did Kirk and McCoy swim down to that entry hatch unassisted, given the depths involved? How can a single volcano possibly pose a threat to an entire planet? [Instantly evoking: a single supernova threatening the galaxy.

] If such a threat does exist, in what way, shape, or form could a suitcase-sized "cold fusion device" possibly do anything to mitigate it? Since when have the transporters ever required line-of-sight access to work? Why are we still saddled with the philosophically indefensible TNG-era interpretation of the Prime Directive? And so forth.)
The picture gradually improved after that, though. I still found myself questioning several creative choices (modern military-style brimmed hats on Starfleet uniforms? Really?), and some plot elements seemed to be there just to provide excuses for "yet another action sequence" (e.g., why would protocol specify the exact meeting room Starfleet brass would use? Why would that room be in an exposed skyscraper with, apparently, no shields or security systems nor any emergency beam-out capacity? Why would Harrison, after operating behind the scenes, put himself at risk by perpetrating a personal attack in a one-man vessel?). And I thought Pike's death was handled rather cheaply.
*But* OTOH I liked the political allegory that was set up in terms of Marcus's plan to take out Harrison without due process, and moreover to do so from a distance using drones (excuse me, torpedoes) in blithe disregard for the sovereignty of another nation (excuse me, planet). This is the kind of thing that real Trek always did well. And when Kirk finally got his head out of his ass, in the wake of his very out-of-character confrontation with Scotty, and made the command decision to go in and apprehend Harrison alive rather than nuking him from a distance (and risking a war to boot), that was the first time I got a glimpse of Pine's character maturing into the real Kirk, the Kirk we once knew, as opposed to an immature and impulsive jerk who relies on luck, as he was throughout ST09 and as Pike had accurately accused him of being.
After that it had its ups and downs for a while, but at least kept things relatively interesting. The brig confrontation with Harrison was a high point, not just because it was a relatively rare scene that made time for actual extended conversation but especially thanks to Cumberbatch's acting, even if the revelation of him as Khan fell somewhat flat — as others have noted, if he doesn't resemble the original Khan in either appearance or temperament, and doesn't share the same motivating backstory, or indeed much of one at all, then there was really no reason to make him Khan as opposed to, say, Joachim or even Garth of Izar. (Even the "familiar name to general audiences" rationale doesn't make sense, since the PTB went to such lengths *not* to publicize the character's identity.) I also liked the prospect of Kirk and Khan working together, and I really wish that had played out longer, rather than having Khan revert to stereotypical wild-eyed maniacal villain mode. However, the intership action sequence involving them getting aboard the Vengeance was interminable, and really seemed like something written just to provide an excuse for 3D effects, or perhaps a video game.
It was downhill after that, unfortunately, as the film degenerated into standard "Hollywood action movie" tropes. Outer-space chase sequence and shootout... yawn. Falling from moon to Earth... yawn (and as others have noted, there's no way it could happen remotely as fast as depicted under the influence of gravity alone; and moreover if the ship's autogravity was off as it tumbled, the crew on board should have been in freefall, not falling this way and that between decks). And then the TWOK-evoking death sequence... excruciating, with no emotional effect except to forcibly remind me of how the same scene had been done better before. And apparently Earth (including Starfleet HQ) still has no air defenses of its own, despite the Narada attack the previous year. Big city-destroying crash... totally gratuitous. Spock deciding to chase down Khan one-on-one... totally stupid (and apparently Earth has no law-enforcement authorities on the ground, either). The fistfight aboard the flying what-were-those-things-anyway-that-looked-like-they-belonged-in-
Star-Wars was (yet again) clichéd and interminable. And while it was nice to at least have a denouement (I'm always surprised how many movies today just dispense with that entirely and end right after the climax), it felt both predictable and tacked-on.
Other general criticisms? The transporters were once again useless whenever they were actually needed, for the flimsiest of reasons (yet somehow Marcus was able to use them right through the Enterprise's shields). Warp travel is still being treated as instantaneous, even more so than in ST09; being only minutes away from the Klingon homeworld makes no sense whatsoever. It was annoying to see the Enterprise interiors festooned with bridges and catwalks that seem to serve no purpose except to give people something to fall off of during a crisis. The blood-based life-restoring serum joins "transwarp beaming" as a miracle technology that fundamentally alters and undermines the whole foundation of the Trek universe, or would if it were taken seriously. And the story outline in its broadest terms has way too many elements (Enterprise is ambushed and outgunned by much larger enemy ship, limps back to Earth, saves planet by defeating the villain with his own superweapon) that seem like a rehash of ST09.
Another poster summed it up best, I think, by calling it "a Star Trek-flavored action movie." But it doesn't measure up to the best Star Trek, not by a long shot, nor does it measure up to the best action movies. Regardless of how much money it makes, regardless of whether or not it creates new fans, what this franchise desperately needs in order to work
creatively is
smarter writing, nothing more and nothing less.