Potential spoilers ahead. I will try to keep it general, but, y'know. Schpoilers!
Then again, if the fact that there are fight scenes in the movies are going to spoil Thor : The Dark World for you, there is a good chance you wandered into the wrong theater.
In any case, yinz guys have been warned, n'at. Onward!
Thor: The Dark World is a touching tale of two men who were caught in a storm which encompassed the whole world.
Hmm. I pulled that off of a random imdb.com comment, trying to be ironic. Turns out it's a pretty good description of the movie. The two men in question are, of course, Thor and his brother Loki. Chris Hemsworth does a great job as Thor, which is to be expected. As for Tom Hiddleston as Loki... look, can I be honest with you? Truly, truly honest with you?
By the end of the movie, I was rooting for Loki.
Hiddleston did a great job in the original Thor and again in The Avengers. In T:TDW, though, he really stepped things up. It would have been so very easy for him to let Loki come across as just another comic book villain. Instead, he managed to paint a picture of a very complex character who has his own loyalties, motivations, and desires. Loyalties that can sometimes make him an ally; motivations that are not always clear; and desires that are more tragic flaws than "evil for evil's sake".
The rest of the cast did an adequate job. Natalie Portman is a bit meh, particularly when compared to her portrayal of the character of Jane in the first movie. The other folks in the movie turned in decent, solid performances, though they seemed... more flat. Not bad, mind you, just not as real as they were in first movie.
A notable exception to that is Stellan Skarsgård. I have seen some people complain that his depiction of Erik Selvig as an addled nutjob fell flat, the assumption being that his character was intended as comic relief. Halfway through the movie, I would have agreed... just up until the point where he turns to another character, and says, deadpan, "I've had a god in my head. I wouldn't recommend it."
Ye-owch. For me, those two sentences put Erik under a whole new light. Thor and the Avengers might shake off a fistfight with Loki, but when mere mortals tangle with those same forces, damage will be done, and will take longer to heal... if it ever does. (Which makes me wonder how well Hawkeye is dealing with his particular instance of having Loki scramble his skull, eh?) As the Marvel universe movies develop, I sincerely hope we see less of the loony madman from T:TDW, and more of the original Erik Selvig as his character recovers from the events in The Avengers.
Oh, the plot? Bad guy shows up. Tries to get his hands on a superweapon that can destroy the Nine Worlds. Hijinks ensue, things get blown up, redshirts die in interesting ways. In the end, the good guys stop him, after a really cool fight scene that literally rages across multiple worlds.
I mean, come on. It's THOR. What did you expect?
Two thumbs up. Good flick. Grab some popcorn, come for the fight scenes, stay to root for Loki.
OK, now for some general comments...
I really liked the fact that they took the opportunity in this movie to cement the fact that the Asgardians are not gods. They have incredible technology, true... but it is technology that is at least understandable, if not yet reproducible by us mere Earthlings. Along these lines, the scene with Jane in the Soul Forge was particularly good for a chuckle.
After this movie, I find myself wishing we could see Sif, Fandral, Hogun and Volstagg in their own feature film. I want to see more of Fandral, in particular. There were more than a couple of scenes in the movie that made me think, "Would I pay money to watch these four fight alien space pirates? Why, yes. Yes I would."
The traditional Marvel "sneak peak" in the end credits was... interesting. There was a definite Star Trek:TOS look and feel going on there. I don't know if that was accidental or intentional. Does it imply something about the part that the Collector will play upcoming Guardians of the Galaxy movie? When we saw Thanos at the end of The Avengers, his role was pretty darn clear: Big Bad. In contrast, the Collector is a Loki-like character, in that he has his own plans and motivations. While he is a sometimes opponent of the Avengers, he also has his own history with Thanos, so... yeah. Somewhere there's a Facebook entry that says, "It's complicated".
Finally... someone in Asgard really needs to talk to Nick Fury and get a loan of some SHIELD advisors to beat some sense into the common Asgardian foot soldier. Seriously, guys? Enemy space ship crashes into the freaking palace, slides to a halt within spitting distance of Odin's throne, and... you advance on it with shields and swords? You're chasing someone back to that same ship, trying to keep them from taking off, and you deal with a single opponent in your way by piling on him in hand to hand combat instead of, say, splitting your forces so you at least have a chance of accomplishing your mission?
I know, I know. You Asgardians have this whole "Nordic Warrior" motif thing going. That seems to be working for you, I guess. Mostly. Kind of. I'm just saying that maybe you should look into the concept of things like ranged energy weapons and cover fire. Oh, and could you at least pretend that you're interested in learning some small squad tactics? That would be swell.