Disagree entirely. Being a group film, individual character arcs don't take centre stage, but every character has their own issues within the film that are dealt with by being part of the team. It's pretty genius in its structure actually.
Iron Man sheds some of his ego, inspired by Rogers' old fashioned heroism and embraces a more selfless and team oriented mindstate. Stark's care-free approach to life has a profound impact on Banner, who finally strikes a healthy balance between himself and Hulk by learning not to repress the other side. Captain America is validated by the end of the film when he is not only appreciated by the other team members as a leader, but by the public as a hero as well. He is still a man out of time, but the world still needs him. Thor reflects on his naive hunger for war, profoundly affected by the mortality of Caulson. Black Widow develops a consciouss, and admits to the truth in her interogation of Loki. Amongst the other heroes, she sees an opportunity to wipe the "red from her ledger".
More than just a group of egos clashing, each character has their own unique struggle that is rectified by being in the group. By interacting with eachother, everyone becomes a better person.
The Hulk thing isn't really a plot hole. I think maybe it could have been clearer, but Hulk in the hellicarrier is a repressed beast under the influence of Loki's magic, whereas Hulk in the final scenes is a willlingly unleashed and embraced character. Vastly different contexts. It's not a plot hole, it's a character development.
