1. The Plot
Theres nothing revolutionary here, its all standard stuff. (Insert Villain) threatens to destroy/conquer earth, (insert hero/heroes) must battle to save it. This template serves its purpose time and time again, its good, it works, but its not mind blowing either. This isn't such an important factor when establishing the value of a blockbuster, but when it comes to 'greatest of all time' territory, average just ain't gonna cut it.
2. The Antagonist(s)
Loki is solid, but for me hes not the epic villain that the film really needed. Surely a film based on a team of superheros needs at least a more threatening villain or a team of less threatening villains? Again, Im no comic book expert, and I know Loki is a god/ demi-god or whatever, but theres just nothing about him in the film that makes you think shit, this guys pretty damn badass!. Yeah but its not just him, he has a badass army of alien type people trying to mess crap up, true you make a good point. But who were they? Maybe someone with knowledge of the comic book verse can tell me in the comment box below, but for the casual viewer they were just faceless, nameless villainsand for bad guys to be truly threatening they need to have a recognisable personality to them. If you ask most people who the best super-villain has been in recent years, Im sure the vast majority of people will say The Joker. Why is that? He has no excessively threatening abilities or powers afterall, except perhaps his winning smile. What makes him such a great villain is how well crafted his character was (and of course Heath Ledgers performance). There was a real sense of evil, a kick ass sinister streak and this depth of character was what made him so threatening. Loki didnt have this; the strength in character just wasnt there and he never truly felt like a force to be reckoned with.