Who Doesn't like Loki?
Yes, I do like Thor as well, but every good movies needs a good "villain". In this particular review I am going to assume that you have at least seen some of the Marvel comic book movies and are familiar with a number of the characters.
Loki is caught fairly early on in this movie, maybe too easily, anyone not trust Loki? The group become divided after Loki's capture, they are divided in how to deal with Loki and the governments plan to deter aliens. Loki manages to escape, surprise. If Loki is to rule the earth he needs to defeat the Avengers publicly. Then and only then does Loki have a chance to rule. It is at this stage that the aliens make an entrance, just to keep things interesting.
Being a Hollywood movie, the good guys were always going to win, being a big budget Hollywood movie the special effects are just what you would expect, I.e. very, very good. It is a fast paced and does have comic moments at times, well worth seeing.