Interesting film, but also unsatisfactory. Yes, the film gets across the dreariness of Jimmy's life, but is not really credible. His father abandoned him and his mother when he was a small kid, apparently because he couldn't settle back into civilian life after the war. It is possible to understand that, if not condone it. Jimmy, on the other hand, does the same (inevitably) to his wife and kid at the end of the movie for purely selfish reasons. His character has no redeeming features. Despite being academically bright, he decides to chuck it all in for no clear reason. He then treats women as disposable bonkees, and deliberately avoids helping his friend (Ringo Starr) when he's being beaten up. He also sleeps with his wife's best friend the night before the wedding. At the end, we really don't care what happens to this selfish prick!
The music, on the other hand, is great! One star is for the soundtrack, which is no longer available, unfortunately.