It is what it is, and a little bit more.
One thing I do with movies is that I don't just watch them, I rewatch them. First impression: Thor is an entertaining summer film. Second impression: an entertaining film in which one can find subtext and subtlety with some effort.
The director's willing to let the camera find the significant details rather than tell you what's going on (the voiceover backstory intro notwithstanding). A shot of Thor on his knees looking at Mjölnir shows you why his Heroic BSOD
goes from bad to worse, and is the only
explanation for his character development in the second half of the movie. In a Michael Bay flick, this is a weakness; in Thor it works both for the "film" and the "summer flick" features. If you're not going to look for detail, you don't need it; the scene works perfectly because his failure is all you need. If you do like detail and do want the explanation, it's provided. In short, this film has something for everyone (But no Male Gaze
. Though there is a shirtless scene for the ladies. And gay men.)
And for character arc, the three act structure sets that up fairly well. Thor spends thirty minutes proving he's a god, then thirty earning the right to be a god, then thirty proving he's a king. If you're here for action and messianic archetypes, look no further; the film hands them to you on a silver platter and you've got a fun evening. If you want to explore the character development wherein an old testament god becomes a new testament god by way of discovering his humanity, then it's right under the surface.
A theme of the movie is that Right Makes Might
. A deeper theme is at Thor's aborted coronation: Mjölnir holds the power to create or destroy. It's not that you can fight, nor that you want to fight; it matters why
you fight. To prove you can be a god, first you have to prove you can be a man. If you want to take a life, you should be prepared to give it.
As always, the most confusing (interesting) character is the villain. Why does Loki do what he does? Is it for the Lulz or the Evulz? Is he jealous of Thor or does he want to help him? Does he want to protect Asgard or destroy it? Whose approval does he seek?
I suspect not even he knows, and that another film will explore it in depth. Mjölnir's duality is also embedded in Loki's conflicting inner selves.