Spoiler Level: Low, but if the movie had any surprises worth spoiling this would be a better review.
Note: This review is of the 2-D version; I've yet to see 3-D improve a movie, and I very much doubt it would have improved this one.
The Marvel comics version of Thor, God of Thunder, is not an easy character to translate to the big screen. Even in the comics, the character has always been slightly one-note: a bold and brash oaf who speaks in oaths and proclamations that range (depending on the writer) from faux-Shakespearean to faux-Biblical nonsense. Even when the comic was at its best—during Walt Simonson's mid-80s run, for example, which showcased the hero's mythological roots and added some much-needed humor—Thor was always the least interesting character in his own book, the dull straight man in a colorful universe of scheming and squabbling gods, demi-gods, giants, and demons.
So the good news about Thor, the new film by Kenneth Branagh, is that Joss Whedon has himself an excellent God of Thunder for next year's highly anticipated Avengers movie. Chris Hemsworth is the bright spot in this otherwise unremarkable slog-fest, and manages the very difficult trick of playing big and brash without playing dumb. His Thor is considerably more charming and affable than the character has ever been on the page, and I'm looking forward to seeing what he brings to a smaller role in what one hopes will be a better movie.
The bad news is...well, pretty much everything else.
Thor is a crushing mediocrity, a passable but forgettable entry in the Mighty Marvel Movie Franchise. (Next up: Captain America.) I can see where someone thought Kenneth Branagh was a clever choice to direct this movie: he has previously succeeded in making Shakespeare accessible, so why not the faux Shakespearean intrigues and cadences of Asgard? Branagh also has—as he showed in Hamlet—a nice (if unimaginative) way with spectacle.
Unfortunately, no one stopped to consider whether Kenneth Branagh could do action scenes, which it turns out he can't. (Anyone remember the inadvertently laughable climax of Dead Again?) Worse, no one bothered to see if Will Shakespeare—or even Branagh himself—was available to do a quick polish on this lifeless, by-the-numbers script.
The obligatory plot synopsis: In the mystical/trans-dimensional realm of Asgard, Odin (Anthony Hopkins) rules over a race of immortal warriors who protect the universe. (Dull-witted Nordic ancients on Earth understandably mistook the Asgardians for gods. They must have gotten a few other things wrong too: since when is Odin, God of War, such a peace-loving do-goodnik?) Odin has two sons: Thor—a blonde, good-looking, boisterous warrior—and Loki—a dark, skinny, sinister magician.
(No spoilers here, but—even if you don't know anything about Norse mythology—see if you can spot the villain. Go ahead, take your time.)
As the story begins, Odin is preparing to name Thor his heir—but then Thor impetuously blunders into the neighboring realm of Jotunheim, and clumsily rekindles a war with the Asgardians' ancient enemies, the Frost Giants. So, instead of giving him the crown, Odin strips Thor of his powers, takes away his hammer, and sends him to Earth for a little time-out. (Odin then quickly falls into a convenient coma so Loki can take over the throne.) Meanwhile, on Earth, Thor meets astro-physicist Jane Foster (Natalie Portman, who just screams "astro-physicist" to me), who has discovered evidence of the rainbow bridge to Asgard that government agency SHIELD would like to quash.
To the extent that it is "about" anything at all, the movie is supposed to be about Thor learning humility and gaining wisdom among the humans, and thus becoming worthy to once again wield the power of Thor. The problem is that this "character arc" hinges on his "relationship" with Jane Foster—which is practically non-existent. Portman has no character to work with, and she has never been an actress capable of rising above her material. And though the two do a fair amount of running around together—and though she becomes a bit flustered when he has his shirt off—Portman and Hemsworth have zero chemistry, and there is nothing even remotely resembling a romantic sub-plot at work in the script to help them out. At the climax of the film Thor faces a supposedly difficult choice about sacrificing his relationship with Jane, and this would have been a considerably more moving plot device if he had any kind of relationship with Jane.
Okay, so some would say we shouldn't go to a comic book action movie hoping for well-developed character arcs or believably romantic sub-plots. (I might respond, Of course we should, but that's a discussion for another time.) The sad truth, however, is that Thor doesn't work as an action-adventure movie either; it lets down the comic book elements just as badly as the human elements. The plot has no scale, no excitement, and no surprises; someone involved in the film is clearly familiar with Simonson's run on the comic book—there are cherry-picked elements and images—but that person obviously just skimmed, and didn't bother to absorb what made those stories work. The action scenes are dull, infrequent, and poorly weighted in the script: the best fight scene (the battle in Jotunheim) comes very early, and all the others—including the climax—seem small and cheap in comparison. The special effects are lavish but unconvincing: the ease and affordability of CGI might allow every director to create worlds and armies, but that doesn't mean every director is going to be good at it. Thor's frost giants, for example, are no more convincing than I Am Legend's grimacing hoardes, and Asgard—while pretty—never for a moment seems like anything other than green screen.
Thor isn't unwatchable—it's nowhere near as bad, or as unfaithful, as the Fantasic Four movies, for example—but that doesn't make it worth watching.