Sin City (the comic and the movie) is certainly not for all people. Personally, I would have preferred an adaptation of Frank Miller's 'Hard-Boiled', but I was happy with what I got.
I'm glad that a parallel conversation has sprouted here about the nature of comics. For people like LSPE and other non-fans who dip into the world of comics from time to time, I'd like to recommend these two books:
They're both fascinating reads and go a hell of a long way in "explaining" what comics are all about.