I'll put this very simple: IT ROCKED!!!
I thought the movie was great, even if it was a little under the quality of the first two. I liked that the storytelling was gutsy (even if it did suffer from too-much-in-too-little-time sindrome at parts) and that actions had consequences, no apologies. The movie was more comic book-y than the parts 1 and 2, but it wasn't cartoonish, and I thoroughly enjoyed the various nods to fans of the comic. It wasn't flawless, and there were a few things I could have done without or with more of, but overall I left the theatre pleased and psyched, as did my non-geek wife.
I'll come back later with a spoilers-included full review.
X-Men: The Last Stand - 4 out of 5 stars.