After an invasion in order to attack the race known as the Frost Giants (enemies of the Asgardians), Thor (Chris Hemsworth) is stripped of his powers by his father, Odin (Anthony Hopkins) and is banished from Asgard, a mythical world based on Norse legend, and sent to Earth. Thor is introduced to scientist Jane Foster (Natalie Portman) and is has to get her help in order to get back to Asgard, in the mean time, Thor has to get used to life on Earth as well as get his mighty hammer Mjölnir back from SHIELD.
So The Incredible Hulk features great relationships and Iron Man features some great humour and interactions but what does Thor bring to Avengers Assemble? Character development. Thor and Loki (Tom Hiddleston), his brother, both go through some deep character development. Thor learns to cope with human life (with some hilarious consequences) while Loki...you know what, I don't think it qualifies as a spoiler anymore ever since Avengers Assemble as it rubs it in your face, Loki becomes the main villain and is certainly a dark villain (until Avengers). Maybe it's because he's British and all the best villains seem to be British...talk about a cliché.
I need to address something from this film. Iron Man 2 introduced Black Widow so that's four members of The Avengers but with one film left, who's the last member who doesn't get a film? Hawkeye (Jeremy Renner). Apparently he wasn't good enough to get his own film or even be a main character like Black Widow was. Hawkeye only makes a cameo in one scene. Sure it's brief but I had to address it or else people who haven't seen Thor (and I just spoiled Loki's treachery) and would be confused that Hawkeye comes out of nowhere in Avengers Assemble considering he's the first member shown in it.
Sure, Iron Man and it's sequel are the humour that makes up Avengers but that's not to say that Thor isn't funny. It is. It's actually pretty hilarious. The things Thor does when he's trying to cope with human life ("ANOTHER!") as well as their reaction to finding Thor. There are also Thor's friends back on Asgard such as Volstagg (Ray Stevenson) and Hogun (Tadanobu Asano). While they are serious characters that take part in most of the action, it's their downtime after Thor's banishment that really makes up some of the humour...mostly Volstagg.
Thor may not be the best member of the Marvel Cinematic Universe but it isn't the worst. It holds up as a solid film that mixes a number of different things together well. Humour, action and character development are some of best parts that make up Thor and it is a treat to watch.
A good iteration to the Marvel Cinematic Universe that manages to mix everything together nicely.