To be completely honest, I never saw the first Thor film. I did slightly familiarize myself with The Avengers (which I wasn't a huge fan of apparently, judging by my falling asleep after the first 45 minutes), but I've just never been a superhero movie fan. Personally, I feel like superheroes are nearly impossible to relate to. I view them merely as buff, otherworldly men with the abilities to destroy just about everything, one way or another. I like characters that you can become vested to; characters that you feel you would portray if your life was made into a film.
Therefore, I do not know if it is at all fair for me to make a review on Thor 2 since I'm barely qualified for not understanding the previous stories. Fair or not though, I shall give my report. ;)
Firstly, I would like to say that I was a huge fan of the film/design aspects of this movie. I always love a movie with nice cinematography and fancy CG (and Thor certainly possessed both). I also thoroughly enjoyed the appearance of Asgard, and I recall leaning over to my friend and commenting on how pleasantly realistic it seemed. So in short, the general design of the film definitely receives applause from me.
Next, I'd like to cover the acting/characters in the film.
I've never really been a Chris Hemsworth enthusiast, but I will say that he did a really great portrayal of Thor. While most girls swoon over his muscular build, flowing blonde hair, and deep, grandiose voice, I merely appreciate these characteristics as I believe they make the character very believable (I mean, who wouldn't imagine the "god of thunder" to be anything but impressively built and at least slightly attractive?)
While I'm not familiar with hardly any of her other work, I believe Natalie Portman did personify Jane Foster quite well. An Astrophysicist, Jane is pretty, agreeably-mannered, and intelligent, and is Thor's love interest. I think Portman did very well in emoting these characteristics, and therefore, I found Jane to be a very likeable character.
Ah, Tom Hiddleston. I shall try my hardest to review his character Loki without completely losing my head to fangirling.
I'm a huge fan of Hiddleston. As a person, he comes across as very humble and happy-go-lucky, whilst maintaining that posh British charm. As Loki of Asgard, he is intense, slightly sadistic, and entirely darkly humorous. I'm almost always a person who glorifies a good villain, and Loki is no exception. He was by far my favorite character in the film.
Other main characters such as Odin (Anthony Hopkins), Heimdall (Idris Elba), and Malekith (Christopher Eccleston) were also acted out with the perfect amounts of valor, intensity, realism or, in Malekith's case, a believable supply of darkness and tyranny, and I applaud all of the actors in their work.
All in all, I found Thor: The Dark World to be a very well-executed Sci-fi/Fantasy action/adventure film with a grand cast and fantastic design.