I am always mystified by people who find movies ruined if they know plot details beforehand, but if you are one of those mystifying people, and unaccountably have not seen the movie yet, here be spoilers.
There have been quite a few interesting comments on the movie, trying to weigh out what has been changed and what has remained the same. See Daniel Larison, for instance, or Peter Suderman, or Steven Greydanus. As I've said before, I think it takes its place as one of the fun movies of the franchise, in the company of The Wrath of Khan (with its relatively clear story and the one villain in the whole history of ST that manages to be both plausible and gloriously over-the-top) and The Voyage Home (with its great crew interaction and genuine humor). A number of other movies had strengths -- The Undiscovered Country has some great dialogue and so forth -- and so forth, but a feature film needs to be genuinely fun, particular since Star Trek seems to have difficulty coming up with more than TV-movie plots. In entertainment Fun covers a multitude of sins.
One of the things that makes it difficult to weigh this film is that we don't actually know where anything is going, and this movie may come to be seen as stronger or weaker as a reboot depending on how well the other movies follow up on it. Here's what I think should be a big issue in films to come. The destruction of Vulcan, one of the chief pillars and founding members of the Federation, cannot go without effect. In terms of the previous continuity (or quasi-continuity, which is as close as it sometimes got to continuity), it seems clear enough that Earth and Vulcan were the key members of the Federation, engaging in a partial division of labor. The Federation was built on Vulcan technological and scientific infrastructure; while its role was often never well-defined, it seemed clear enough that the Vulcan Science Academy was one of the most important, and (given the nature of the Vulcans) probably the most important research institution of the Federation. Earth, on the other hand, was the primary foundation for Starfleet itself, in all of its functions: exploration, policing, defense. Humans are always presented as the ones giving vivacity to the Federation: rushing in where angels fear to tread. Vulcans gave it strength and caution: logic, whatever that was thought to mean exactly by whichever writer was writing at the time. There were other species and civilizations that played their roles, but over and over this was clear: the two powerhouses of Federation politics and policy were Earth and Vulcan. This whole scenario has changed. The Vulcan powerhouse is now a minor colony struggling to survive. The Vulcan Science Academy is shredded. All the ties of economics, research, and production linking Vulcan to the rest of the Federation are severed. This is a massive and terrible wound for a Federation that still must handle Romulans and Klingons, as well as all sorts of other dangers. Imagine what the U.S. would have been like in the Cold War if California had unexpectedly and catastrophically collapsed into the sea. In The Undiscovered Country the Klingon Empire was brought to its knees by the destruction of a single mining planet. No doubt the Federation is more stable, but it's also suffered a far more serious blow. If you're brash enough to kill six billion Vulcans, ruining the great civilization for centuries at least, you'd better follow through with the consequences.
The natural result of this would be desperation. The sharks are swimming out there beyond the borders and there is blood in the water. The whole government of the Federation, if it is not completely oblivious, will be worried. Who will try to take advantage of this weakness? What can be done to stop them? How can the Federation compete with rival nations? Can Federation values be maintained in the face of the needs of survival? Everything is unstable and in doubt; the continued existence of the Federation is in the air; and it will take all of Starfleet's best to keep things from spiralling out of control. In fact, if the producers play their cards correctly, what we should see in the next several movies, and certainly the next movie, is that things are doing precisely this: spiralling out of control. Terrible war with the Romulans (or Klingons) should be narrowly averted, or (if war is not averted) the Federation should have victory by remaining true to itself; the dangers of Federation desperation (and the consequent temptation to play dirty) should be made clear; and a new equilibrium must be found. And the crew of the Enterprise, as always fallibly but also in the long run surely, first in sheer doggedness and then in triumph, must be there waving the flag of Roddenberry's basic vision: progress and peace, tolerance and respect, discovery and courage. The Federation cannot possibly be the same; it faces a struggle like no other. But the vision has to stay at least more-or-less the same. This contrast is what gives room for genuinely interesting possibilities.
I really don't have all that much faith that this will happen. But it's what should happen. If something more-or-less like it does, it will have all turned out well. And if it does not, people will be annoyed at the unfulfilled potential.
