Okay time for my in depth review of Avengers Age of Ultron after my second viewing. So it does not seem like people are having problems posting spoilers so I won't either. So warning there will be spoilers below.
Once again there will be Spoilers Below if you do not want to read them skip this post.
Now that is out of the way let us talk Avengers. Now I will have to compare this to the original Avengers. Normally I try to avoid comparing movies but I've made the statement, and continue to believe this statement, that this is better than the original Avengers. I will explain why. Now the criteria I judge this on could be different than another's as most of this is all opinion based anyways.
So I thinkhow the characters were handled in this movie was much better than in the Avengers. Yes Whedon tried to give every Avenger one shining moment and some time but in the end I honestly felt like Avengers 1 was the Tony Stark/Bruce Banner show. They seemed to get the best everything from scenes/interactions/good comedy/etc.
I'm going into more detail about the above comment so I can further explain why I think AoU did such a better job juggling the characters.
First major selling point to me was I thought character interactions in this movie were leaps and bounds better than the first. One of my biggest gripes was how stupid Captain America seemed compared to Tony. In Avengers they tried to show how different the two were but it really just came off as Steve seemingly looking pompous and Tony just squashing him verbally. They did a much better job in AoU of having Captain America not only being able to hold his own against Tony but actually making valid and intelligent counter points.
And this goes for all of the characters. Their interactions seemed natural, genuine, and it actually felt like time and effort had been put in to making each character interesting when interacting with another. There is not one scene in the Avengers that comes close to capturing the chemistry of the party scenes in AoU. Not even one on one interactions with characters. And it is not like the party scenes were the only good interactions in AoU it pretty much continued throughout the story.
I also felt, minus Tony/Banner, that the different characters not only did better interacting with each other but that each character was written better in this movie and they each had more impact. In Avengers 1 each character had their moment but often times it was only briefly until Tony/Hulk filled in the rest.
In AoU I felt everyone had much more chance to shine. Now AoU did not perfectly balance every character which is probably impossible and honestly some characters need slightly better scenes and dialogue to be more important like Hawkeye. Or to get them up to speed if they are newcomers like Scarlet Witch and Quicksilver. So adding a little extra focus is okay but I never felt like the other characters were backups to them. Which like I said in Avengers 1 I felt like you could have titled the movie Iron Man/Hulk and friends and no one would have second guessed it.
Now with that being said I did not really like the Black Widow Brice Banner romantic subplot. Although it wasn't nearly as bad on second viewing. Mostly because they did have some tender moments which helped. Still it did seem somewhat forced.
Now I'm going to go over Villains. I actually liked Ultron a lot and think Spader did a fantastic job with this character. The almost child-like way Ultron interacted with the world mixed with a cunning computer was great. Especially the scene where he gets compared to Tony Stark or when he first comes online. Was he has good as Loki probably not but at the same time Tom had already had one movie under his belt to refine the character.
Action wise I think this movie outshines Avengers by leaps and bounds. Every character gets a chance to be awesome over and over. The opening battle sequence was amazing. The Hulkbuster/Hulk fight was great. The final battle I was never bored for a second. Of course this movie did not have the defining Leviathan punch scene like the original Avengers had.
These are the reasons I think AoU is better than Avengers.