There is a lot of sadness in this movie but at the same time with a more or less comedic atmosphere that gives it a casual tone despite the dramatic nature. The portrait and the family relationship is very real and while Dan can be depressing, Steve Carrell was great in the role. My problems were the ending and most of the characters, specially how some relationships were handled or little developed.
Dane Cook is fine in the movie. You guys just don't like Dane Cook. His performance is good too, and it's a very good character. Rare. He's enormously forgiving. Even at the end of the movie he doesn't flip out at Dan for, essentially, stealing his girlfriend.