It was a fun movie to watch and had several great moments, but it tried too hard to make each Avenger important.
Hawkeye isn't as cool as Iron Man. There's no need to spend 30 minutes at the Hawkeye Ranch to make us fret over whether Barton lives or dies.
It's cool to give Natasha Romanoff more to do in Captain America 2, but stuffing a romance storyline into an already bloated movie makes it seem forced.
Maybe removing the movie of those burdens would have given greater opportunity to explain what why in the world Thor needed to abandon everybody to go swimming in a cave.