This will be spoiler-free.
Initially I was very suspicious the idea of Thor as a movie. A second-tier superhero at best, the idea of a movie about Thor generates even less interest than Daredevil did. Moreover, THor seems like the hero least suited for adaptation to the big-screen. This may work in a comic book...
... but it's hard to imagine that picture translating well to the big screen. Moreover, Thor runs into the same problem that movies about Superman run into: he's a god. What kind of stakes can a movie like that have? This felt mostly like an excuse for another Marvel action movie, and one I planned to skip. I see most superhero movies these days, but my time and budget are both quite limited and I didn't intend to go out of my way to see this any more than I did for the remake of The Hulk or X-Men Origins: Wolverine.
I became cautiously interested when I heard that Kenneth Branagh was directing. I respect his work as an actor and he's been very good about selecting his projects. When I saw the final trailer last week I decided to give it a shot at matinee pricing, if my schedule allowed. Thanks to an unexpected opening, it did.
The movie works, and it does so for several reasons. The first, and perhaps the most significant, is that it Branagh has his actors play everything completely straight. Comedy is present, but quite sparse compared to typical Marvel movie fare - much more so than either Iron Man - and is limited to a few low-key scenes. It is completely absent from the scenes that take place in Asgard and the movie benefits from this choice. Quite frankly, Thor has always looked ridiculous and the supporting cast doesn't fare much better. The movie refuses to acknowledge this. There is no point where someone tells Thor, "Your armor looks stupid," or tells Loki, "You look like a confused, retarded, lesbian cat confronting her sexuality" (he does, by the way). Nor does Branagh hide the designs. Instead, he fills his frame with them, early and constantly, so by the time the weighty drama is unfolding the viewer is used to them, if not completely accepting. Moreover, the different visual motifs used for Earth, Asgard, Jotunheim (the realm of the frost giants, ancient enemies of the Asgardians) give each a distinct feel so that we can take Asgard as is, if only because it is distinctly its own realm.
The other reason the film works so well is that Branagh is not content to simply film a comic book story, but seeks to make an epic. I don't know if screenwriters Miller, Stentz, and Payne intended literary allusions within their tale, but the story I find Thor resembling strongest is nothing from the bit of Norse mythology I know, nor even the Greek or Roman pantheon, but rather that of the epic of Gilgamesh.
Gilgamesh, the oldest known story in literature, is about superheros behaving badly. Gilgamesh is a powerful king who abuses his power and so the gods teach him humility, which yields to many a wacky yarn and in the end Gilgamesh becomes a great and wise king. I'm paraphrasing, obviously. At the very least go read a synopsis (here's one). While Thor doesn't attempt to follow Gilgamesh point for point, there are enough similarities that I feel comfortable calling it a spiritual successor.
This use of epic allows for several effects. The first is relevancy. Thor is a story about power. How one acquires power, how one uses power, how power can be abused, how power is shared, how power is lost, what power is good for, and what makes one worthy of power. While The Dark Knight handled the issue better and more effectively, particularly with regard to America's role as either world policeman or self-appointed vigilante, Thor makes a worthy attempt to grapple with these issues. The first act may be intended as a parallel for the start of the Iraq War, but rather than focus on what has already occurred, the remainder of the film deals with the consequences - the unexpected consequences - of what unleashing power has wrought. The film never hits you over the head with the parallel, to the point that I question whether it's even truly there, but the questions about power remain universal in their relevance, so perhaps that's why I'm able to apply them to Iraq. Regardless, it makes the theme quite significant and I applaud Branagh's deft handling.
The second effect of using epic is both the most obvious and the most subtle. Mosty mythologies about deities can be summed up as, "Gods behaving badly." This is just as true of Thor as most other such stories, such as The Illiad, and like The Illiad the effect in Thor is that the gods are humanized. It is easy to see Thor as an arrogant, presumptuous boy who is scared at what it will take to fill his father's shoes and is looking for an easy way to what he thinks is living up to his father's legacy. It is easy to see Odin as an old man who is worried that he hasn't done enough to teach his sons and is punishing them because he's frustrated and doesn't know how to be a better father. And Loki...
I promised no spoilers. I'm just going to say that Loki made the film for me. Everything about the character was perfectly done, from his plot lines to Tom Hiddleston's emotional and moving performance. Loki was what turned the film from camp to an epic.
Even if he does look like a retarded, lesbian cat.
Should you go see this movie? Eh. If you're not a fan of modern comic book movies, this one won't change your mind. If you've enjoyed the last decade's releases from Marvel, however, this is one of the good ones.