I think the run time is fine, but it's not evenly delegated throughout. For example, a lot of time is spent on establishing Hawkeye character and his family, but in the end when he "retires" and goes home, I didn't missed him at all, kinda glad he's gone to be honest.

I liked Hawkeye in the film actually. His scenes didn't really fit into the whole movie, but I just liked that he seemed the most grounded and normal person while everyong else was angsting.

Ultron and Vision were really characters. Lotsa potential, but so shoehorned.

Tony was pretty true to character compared to his recent comic appearances; a megalomaniac self-appointed world saviour and futurist that sees the earth is doomed unless he takes action by whatever means necessary.

Thor... had some dreams and stuff, then came back mumbling about infinity gems. Makes sense for us comic nerds, but probably completely lost on regular viewers. This seriously needed more explanation. I read somewhere they cut the explanation scenes in favour of Hawkeye's farm scene.

Black Widow & Hulk... meh, could have done without this, but I guess everyone needs equal screen time.

Cap... what did he do in the movie again?