I'm not very good at definitions, especially in English, as it is not my first language, so I cut and pasted this definition from wikipedia to explain what I mean:
"Self-deprecating humor relies on the observation of something negative about the person delivering the commentary. Many comedians use self-deprecating humor to avoid seeming arrogant or pompous, and to help the audience identify with them. "
Not that I think you didn't know that, just to explain my thoughts. Because I think this is absolutely spot on, when I read Neil's book.
In the book Neil uses this humor a lot and exaggerates his envy. Now I haven't seen the movie, but from the reviews I've read, it seems this self-deprecating humor gets lost, maybe because he's not the narrator. The exaggerations are still there and therefore he appears arrogant.
A better script writer could have made us identify with him, and I'm sure they were trying to do that, also by making Bono so damned helpful, which makes it worse if you're jealous at him.
I wish they had made the movie more like the Commitments without the mafia scenes. A comedy where you could identify with Neil, like in the book, where he is wiser at the end and happy with his life. It says a lot about fame and what it means to people today (X-Factor, American Idol etc.). It's funny and relevant without being preachy.
From all the articles I've read and the interviews I've seen, Neil seems like a really nice guy, who absolutely loves U2.