AoU does exactly what a sequel should.
There seems to be a fair amount of people who claimed AoU to be disappointing. Although that seems less of an issue now as most of this board seems mainly positive, but on the film's initial release the response was more mixed.
And AoU still has quite a lower rating here than the 1st film while I do hear some take nasty stabs at it here and there. And I'll be honest, I've never really understood why. AoU improves on it's predecessor in every conceivable way yet still people aren't happy. It's a better film.
But I think the problem lies not with the film being underrated, it got mostly good reviews and was disliked by many but loved by a slight majority. I think that's fair. It's more that the first film is overrated. Don't get me wrong, it's a fun film. But it is adored by everyone. Does it really deserve to be put on that pedestal?
If anyone has a decent argument for the 1st film's superiority then feel free to reply. I'm interested. But here's my stance on why the sequel is a big improvement.
Firstly, lets deal with the sequel's detractors. There is no criticism that I've heard that doesn't equally apply to the first film.
secondly, and most importantly, in order for me to claim how the sequel improves I must address the 1st film's flaws.
1- There is little story. It amounts to nothing more than- bad guy wants to take over the world, he gets some aliens to help him, the Avengers stop them. This thin plot directly relates to our 2nd issue.
2-There is way too much exposition. Yes there are scenes of banter, chemistry and character development, which is great. There are also many extended scenes where our heroes hang around talking about trivial crap at great length just to bump up the running time. This does get tiresome.
3-The bad guy sucks. Another thing I'm baffled by is Loki's bizarre popularity. Again, if someone wants to explain it to me please do. Tom Hiddleston is a good actor elsewhere, but here he's hammy and cheesy as hell. A panto villain with little depth.
4-The action is devoid of tension. It's skillfully directed and looks awesome, but the faceless,CGI, cartoony aliens pose no threat. The Avengers slap them aside with ease and as such, we feel no threat. We feel no danger. As such, we cannot enjoy the action on the level we are supposed to.
5-The jokes range from funny (most of which we already saw in the trailer) the meh, to the embarrassingly awkward (that whole Agent Causon "I don't know what this gun does" cringefest).
Yeah, I did enjoy the film. But it's not the peak of entertainment many claim. So here's how AoU accomplishes what a sequel should and improves.
1-The story/themes are more substantial. The film explores the whole A.I. thing. Not very deeply, especially compared to recent films like Ex Machina, but it's still more than the 1st film gave us and thus holds our attention a little better. And because there is more going on we get a lot less exposition. The film flows better.
2-Better Bad Guy. Ultron has more motive, he's more threatening, he's more interesting and most importantly, James Spader gives a much better performance.
3-The Action is way better. The Avenger's battle adversaries played by real people, The Scarlet Witch and Quicksilver, who have interesting, visceral abilities and do pose a threat. Ultron poses a threat.
Yes the finale still has them battling bits of CGI again, but CGI always seems to look more convincing with metal than skin, so it doesn't look quite as cartoony.
When the Avengers fight each other it's actually for a valid reason. In the 1st film when they clashed it felt contrived. It didn't seem organic or natural. It just felt like they were fighting for the sake of it, because the audience wanted to see them fight.
4-The humour is a lot more consistent and a lot more frequent. The jokes are rattled off so quickly and confidently that if they were bad, you didn't notice as much. Unlike in the 1st film which really pushed it's gags sometimes. That Agent Caulson/gun example I used before being a prime example. It spent so long setting it up, dwelling on it, that you really felt the tumblweed blow by if you didn't find it funny. The banter and chemistry is also better. The whole thing at the party with Thor's hammer, etc, etc.
The one issue I do hear people level at AoU is that it spends time setting up later films whereas a film should be a complete story. Ok, but Civil War spent a lot more time doing the very same thing and even ended unresolved. Yet the film was universally celebrated. I personally don't find this element a problem in either case, I even quite like it. But you can't criticize one film for something but not another for doing exactly the same thing. Criticize both films or neither.
So that's why I feel AoU is the more deserving film. If you disagree fair enough. But I do think that with the 1st film people got swept up in the excitement and remember it as better than it actually is. It's this memory people are comparing the sequel to. A memory that no sequel could ever match.