Glad we nearly agree :-)
I think the opening speech is one of the best written things I'd heard in ages (doubly so with Depp's delivery).

I don't think you have to like him to enjoy the film.
Certainly the actress Samatha Morton plays is more engaging.
I also found how the other characters dealt with Depp to be engaging.
Mind you, I still cared about Depp's character even if he was unlikable.
His passion and rebellion was likable, as is his final realisation that he needs to stand for something.

I also rather liked the grim reality of the film for the less than romantic picture of life in the period.