Finally watched Thor. I had plans to go with a bunch of people to see it when it was out, but had to cancel because of illness.
Not bad. Not the best, but a lot of it was fun. My biggest complaint would be the cgi Frost Giant stuff looked too video gamish. The guy playing Loki was spot-on. I've read the mythology since I read the comic, so that's what's in my head now, but I thought he embodied Loki nicely, particularly in the first part of the movie. Loki always made me want to root for him, even though I knew I shouldn't. The whole thing with Loki being Slepinir's (Odin's horse) mother always made me feel sorry for him.
Thor was better on Earth than he was in Asgard, but the early odd couple stuff between him and Loki was pretty on target as far as mythological tone goes, which is hard to do given the factual changes between myth and comic. I would guess that Kenneth Branagh, given his classical pedigree, is pretty familiar with the mythology.
As far as Avengers precursors go, I'd rank it behind Iron Man and Captain America, but well ahead of Iron Man 2 (can we just forget that happened?) It was nice to see Hawkeye show up during the movie itself.