Saw it yesterday.
1. Benedict is outstanding. Only now I grasp fully the meaning of word "mesmerising".
2. Benedict is devastatingly handsome as John Harrison
3. Did I mention that he gives an outstanding performance? Ah yes, altitude sickness, you know
4. I enjoyed the movie. Did I? Yes, I definitely enjoyed the movie. It is true that I had to switch off my intelligence in order to gloss over gaping plot holes and some cringe worthy dialogue lines, but I have no problem with it: action movies are not famous for logical plot development.
Also, the movie has at least three good premises: the idea of tackling the issue of the "enemy within" and moral questions related to it, the idea of Kirk's journey from zero-to-hero (ok, it is kind of hyperbole) and the concept of the villain (s). Benedict did a phenomenal job, but he still needed decent material to work with and he got it. So... kudos to Abrams.
This said, the movie has also some serious flaws. I can think about several, but one which is evident to me, is that Abrams was not really able to decide who is he addressing his movie to: Star Trek fans or new audiences. He tried to do both things, unfortunately missing the mark. Many of the movie twists/ issues rely heavily on knowing ST lore and are not so much incomprehensible as not effective if this knowledge is lacking. For example, we need to have a background about Kirk - Spock friendship and Vulcan's mentality, to feel a dramatic tension of the initial prime directive dilemma in the opening sequence (well, be honest, even with this knowledge the tension is not really there). As a result, the appeal of the film for the newcomers depends mostly on the charm and originality of Benedict's villain: it is not surprising that the trailers focused on him almost to te point to create false expectations about his part in the whole movie.
Also, from this point of view making Benedict into Khan doesn't really work, because for a non Trek fan it adds nothing to his performance and character.
On the other hand, Abrams eagerness to please ST fans and his clever (or not so clever) idea to reboot canonical villain was met with rage by many hard core trekkies and resulted in many nods to Original Series, which are neither motivated nor interesting: the character of Carol Marcus is completely meaningless, and old Spock's cameo positively annoying. All these nods are empty fillings in the movie's plot and steal precious screen time which can have been used for a better exposition of nodal themes of STiD, IMO.
So, as I said, the film is entertaining and thought-provoking, which is more than can be said about most blockbusters. Plus, BC is a joy to watch. But I have also a feeling of a wasted opportunity: coming from such a strong starting point, it could have been much more brilliant movie.