So, my measurement for whether or not a sequel is good is if I can walk away and say that I liked the characters more/the same than I did before I watched the movie.
And that was totally the case with Thor. From Jane to Thor to Loki (believe it or not because I'm not the world's biggest fangirl of him) to Frigga (dude, Frigga!) to Heimdall (who, I admit, might be my favorite minor Marvel character ever), I grew to love them even more.
It has its differences from the first movie, of course. And[pipsqueak spoiler here]there is a noticeable absence of SHIELD, but there was a cleverness in the movie that I loved. And the big ending scene? Brilliant.
Was it better than Thor 1? I'd have to give that a yes. And if I didn't have such a bias towards Steve Rogers, I might be willing to say that, The Avengers excluded, this is the best Marvel movie yet.