It was good.
Chris Hemsworth was perfect in the role, most other actors were good (Idris Elba was great a Heimdall - but that may have had something to do with the post-processing on his voice). Natalie Portman was solid, as was Stellan Skarsgård.
I did feel that Anthony Hopkins could have done with a little more Oomph as Odin. It's not that he was bad - it's just that he didn't have quite as much presence as I felt The Allfather should have. Likewise, Loki wasn't bad, but I felt that he could have done with more of a sense of humour, or something like that. As it was he felt either calculating or stroppy, but only really clicked for me in a couple of scenes.
Overall though, good fun. Asgard looked fantastic, the battle scenes were impressive, and there was a nice sense of humour about it.
Next up - Captain America in July, then a whole year until The Avengers!
Original post on Dreamwidth - there are comments there.