Liked the movie. I thought it was better than the first.
I was pleasantly surprised by Frigga's portrayal, considering Rene was way underused in the first movie. The line about Loki getting his 'tricks' from her, awesome. It served well to give a little insight into the family dynamic. That scene with her fighting Malekith was great. If Kurse hadn't shown up she would've kicked his ass. I actually cared when she was killed and made me connect with the other character's motivations for what comes next, especially Loki.
Odin's characterization, I wasn't too pleased with. I feel it doesn't match what we saw of him in the first movie. I know in the comics he's not the nicest guy all the time but in this movie he was a hot head, and that is a total opposite of what he was in Thor 1. It was almost like a reversal of him and Thor. He was acting like what he reprimanded Thor for being when he attacked the Frost Giants. He definitely wasn't the wise Allfather we saw before. Did it break the movie? No, but it was distracting and confusing. At least for me it was.
Loki was great. Everything they did with him was awesome and Tom did an amazing job, as usual.
I saw some growth in Thor, so that was good. What I did not get is the apparent toning down of his powers. To me it felt like he depended on Mjölnir too much, like without the hammer he wasn't a real threat. That shouldn't be the case at all... You know those scenes in Avengers, when he's fighting Hulk without the hammer and holding his own and when he's fighting Iron Man without Mjölnir and is still able to crush the armor with his bare hands? Those scenes show that Thor is a powerhouse without his weapon. I didn't get that impression in this movie... Maybe I'm being too picky. I'll pay close attention on my second viewing to see if I'm mistaken on this point... But one definite gripe is that it's now official he can't fly or even levitate without the hammer. That's disappointing.
I liked the humor in the movie, but some of the scenes felt misplaced, like the subway scene. Funny as it was, it was unnecessary to interrupt everything else that was going on at that time just to show us that... Plus I was also annoyed that Thor had to take the subway and couldn't just fly there.
Overall, great movie. But there's definitely room for improvement.
Also, the Collector scene... I didn't hate it per se, but it was underwhelming for me. The set looked cheap. That huge cut-out of a blue butterfly looked cheesy and fake, as did some of the other 'collections'. This was surprising, because what little we've seen of Guardians looks great. Let's hope this scene is not a reflection of the look and feel of Guardians.