Our central characters were more natural and confortable in their skins than in the first movie, in which they sometimes verged a little too close to caricature. This time, not only were Kirk and Spock superb, but Bones, Scottie, and Sulu were outstanding, and played crucial roles in the story. Chekov was still and likely always will be a little ridiculous with his Russian accent - I bet the average person who speaks English in Russia today speaks with less of an accent - but that's part of what makes him endearing. My wife Tina wanted to see more echoes of the original Uhura in this movie, but I liked this Uhura just fine.
Bear in mind, as the old Spock explained to us in the previous movie, that what we've been seeing in this and the previous movie is an alternate reality of Star Trek - alternate, that is, in contrast to what we saw in the original and subsequent Star Trek television shows and the first 10 movies, which we can now identify as pre-JAbrams. In most ways, the characters are the same. And most of the original characters are in this rebooted universe. Hence Nurse Chapel from the original series is mentioned in Into Darkness.
But there are differences, which account not only for Uhura - and her romantic relationship with Spock in the J. J. Abrams movies - but other characters including Christopher Pike. In the original series, he ends up in a wheel chair, face disfigured, on a world in which he can live his dreams (Kirk and Spock help get Pike there). In the new movie, he ends up dead - killed by Khan's attack. My wife wondered why he couldn't have wound up disfigured in a wheelchair in the new movie, too. It would have made a nice closing of the loop between the original and current Star Trek realities, and I would guess that J. J. Abrams and his producers and writers didn't want it to close quite so neatly.
They're probably right. What we want are glimmering reflections of the original Star Trek, not a more intense, constant search for similarities and coincidences with the original. Khan, for example, who was a crucial character both in the original TV series and the original movies, was a Khan who in this movie bears only some resemblances to the original. But Old Spock tells Spock about the essential similarity: Khan is a highly lethal danger to Kirk and Spock and the Enterprise.
In the end, people who have seen every Star Trek ever made will have to decide if they think the similarities are too little, too much, or just right. My wife wanted more of the original Uhura - especially because other characters resonated so well with the originals - but I didn't really miss her in this movie at all. But such differences in taste are akin to whether you prefer this touch of spice or that in a great dish. What's undoubtable is Star Trek Into Darkness was one great movie indeed.
See also Star Trek: Reborn, Reset, Resplendent