Dizzy's behaviour/personality traits
I really liked the movie, as there were quite a few funny moments and it has an uplifting message.
One thing confuses me - Dizzy is portrayed as a geek, but I get the impression that even before his transformation he was not really the shy and studious type - e.g. he was a member of a musical ensemble, was quite gregarious, didn't seem too scared to break the rules and stand up to teachers, was willing to ask out a "queen bee" (without even knowing her well). Yes, his behaviour was definitely weird in a number of respects, but he did seem like a fun guy to hang out with and given his size (he was rather tall and could seem slightly intimidating), as well as his willingness to contradict the teachers/pull on a show/be disruptive in class, it's a bit surprising that he was treated like an outcast and picked on by the jocks. What I am saying is that Dizzy exhibited some semblances of jock-like behaviour even before his stint in a prison cell, so I found it odd that he wasn't appreciated by the "tough guys".
Btw, while Danielle was beautiful and very sympathetic to him, Dizzy could have gone out with Nora as well, she was nice, good-looking and really seemed to care about him (though I guess that there is not always a natural continuity from best friends to lovers).