As for my fan credentials, I have this in my office:

Like many other fans, I went into this movie excited but somewhat nervous (from the trailers) that I just might encounter the following:
a) A special-effects and action-driven Michael-Bayish three-ring circus without a compelling story and well-drawn characters;
b) Young, angsty "pretty boy" actors making laughable attempts to step into the well-worn shoes of giants;
c) Decades of "canon" and continuity sacrificed on the altar of being "hip" and edgy;
d) An attempt to recreate the flash and silliness of "Star Wars" without the heavier narrative weight and respect for science (well, at least token respect for science) that "Star Trek" had.
I am pleased to report that my fears were almost (and by almost, I mean 99%) unfounded.
Yes, this movie is heavy in eye-popping special effects, but like all good science-fiction movies, they service the story well. Yes, the cast consists of young and attractive unknowns, but they are all fine actors and they step into the familiar and well-loved roles with ease. The canon and continuity of the original series is not dispensed with lightly; rather, it is set gently aside with acknowledgement and respect. The Star Trek Universe might have changed, but in many very satisfying ways it has stayed the same.
The coolest thing about this movie, and why it is a triumph, in my opinion, is that it undeniably IMPROVES on many things from the original series, because the producers of the original show just didn't have the time, budget, or technology to pull it off. I don't want to give too much away (this movie has already been almost thoroughly spoiled), but there is some business with the transporters that had me laughing out loud, because I always wondered if they shouldn't work that way! And this movie, unlike most of the series following the original (and every movie following Star Trek IV) is genuinely FUNNY. Not funny in a self-parody way, but funny from situations that arise in the film.
And I can't talk about the humor in the film without again giving kudos to the actors. Simon Pegg and Karl Urban are the standouts, as they so happily bring back the fun of McCoy and Scotty. Zoe Saldana has a much meatier and touching role as Uhura. And Chris Pine and Zachary Quinto are simply terrific as Kirk and Spock. They don't mimic Shatner and Nimoy, but they bring back the essence of those great characters, and when the two team up to take on the villain at the end, it's just like we're seeing old friends in action again.
So why was I 99% satisfied? Because as much as I liked the story, it is NOT "City on the Edge of Forever" or "The Doomsday Machine". The story is compelling and it serves to get the cast of characters together on the bridge of the Enterprise, but that's really about all it can do. However, I eagerly await the sequel and all future movies made with this creative team.
So, in summary, let this Star Trek fan say that not only was I NOT disappointed, but I was very pleasantly surprised. This is the Star Trek movie I hoped for when the original Star Trek: The Motion Picture came out. It is easily the best of the series, and it has left me wanting MORE.