Well, saw it last night, and I liked it! I think it helped that the theater was sold out, full of pre-teen fans, and they were all very vocal in their enjoyment. Normally, I get annoyed with the audience taking the focus off the movie, but last’s night experience seemed enhanced by it. Cheering during the proposal scene, lots of reaction to Jacob’s appearance, appreciation of the subtle one-liners in reference to the series, etc.
As a negative, I was actually disappointed by the IMAX print of the film. It seemed grainy not very vivid. I fear I have been corrupted/spoiled by Blu-ray, a 65" TV and a 7.1 system at home, but I have enjoyed other mega-productions (like Avatar) in the theater; this one just didn’t do it for me. One of the things I most appreciated about both Twilight and New Moon was the gorgeous scenery of Canada. I will rent this one on BR when it comes out and see what it looks like there.
I was surprised by how much of the book was included into the movie, and every time I thought to myself that they would gloss over a plot point, they put it in. Maybe I should not have been, but I did not expect inclusion of Jasper’s backstory, or Bree Tanner as much as was there. At times, this much detail drove the movie along ploddingly, where it seemed like they were going out of their way to include all the details at the expense of plot flow. I would have liked more show, less tell in some scenes, and a better handling of the “wolf telepathy” angle. I would have appreciated a more…sentimentally appealing actor as Seth. And geez, enough with the damn kissing every two seconds. 
But I am a fan of “world-building” movies and books, and I do feel like a part of the Twilight universe while watching these movies, just as I do with the books. On that point, I think in was a success.
And Nightingale, I like the angsty! As a 36-year-old guy with no kids, I don’t get too much teen angst anymore, so it can be refreshing to revisit it. :o