A bit longer:
The basic advantage to filming a comic book is that the background is deep and known to a wide audience. Doing origin stories of comic book characters always seemed a waste, though given the twists and turns of the official canon, you might as well pick which origin mythos you're working with.
As a comic book, Thor was never one of my favorites. Partly, the "secret identity" of lame Dr. Donald Blake was pretty, um, lame. A god is a god, and the Norse mythos was already too complicated to add a layer of commercial empathy. And partly, Stan Lee's weaknesses as a writer were out in full force: Full of bravura and action, light on making sense or coherent story arcs.
I would have thought this an easy translation to the big screen. But no. In Thor the bravura is deliberately toned down or played for laughs and the action is incoherent and without force. The 3D was wasted.
The unsung hero of the Spiderman movies is Steve Ditko. Even as a kid, I could tell a Ditko-drawn comic just from how people held their hands. Translating the comic to the movie, the producers had all the characters in classic Ditko stances. The movies felt like the comic, and that was an important element in their success.
The sweeping complex panorama of Jack Kirby splash pages is, I would have thought, an easy translation to the big screen. But no. In Thor, the big splashy scenes are muddy. No majesty, no getting caught up in the panorama. The technobabble, trying to reconcile the magic of the Norse mythology with today's science, was the best part. Indeed, the astronomical photos under the first part of the credits at the end are great, almost worth the 3D in themselves.
The acting was okay, but not better than that. I blame director Kenneth Branagh for not letting everyone play broadly, like a comic book character... or a god. The plot chugged along nicely, but the writing seemed rather lax. No sparkle to the dialog, and everyone seemed determined to move to the next scene at the expense of character development.
Thor is not a horrible movie, and almost everyone else likes it better than I did. Still, it seemed like a big-budget prequel to The Avengers movies than a stand-alone action flick. On the Shockwave scale of 9 to 23, I give Thor about a 13 or 14, depending on how much suspension of disbelief you can muster.
And yes, stay for the vignette after the credits.