I found it hard to have any sympathy for Cobb. I understand why the true story of what happened with his wife was kept hidden for most of the movie but it meant I spent 3/4 of the film wishing he'd either get his mind back on track or get out of the dreams altogether.

I don't know if it was the writing or DiCaprio's acting that made it worse. He was very absent and distant throughout and it harmed the connection with the audience.

Plus, the rest of the team were pretty awesome (Arthur and Ames especially) so as a protagonist, he was dull and boring compared to them.