... not the movie, but the number of self-professed Holmes aficionados who apparently have no knowledge of Holmes. For the record, Holmes was a miserable, irresponsible drug addict who did indeed sleep on the floor, insult his best friend, experiment on his dog, and never ever wore a deerstalker's cap (at least, not until television was invented). He was a brawler who practiced martial arts and was as likely to slum around in the filthiest of rags as he was a suit.
It wasn't until after Doctor Watson took him in hand that he truly refined himself and became a "respectable" member of society. And yes, we can tell that this movie takes place THAT early in their relationship because Watson has not yet married his wife (the retconning did annoy me, too, by the way, but you just can't avoid a little re-imagining here and there).
Speaking of unavoidable, Irene Adler, Holmes' one uncapturable (is that a word?), simply had to be cast as a potential love interest. The flirting, the romance, and the near-make-out session were irresistible to the director (and to all of the audience who're honest with themselves).
That being said, I felt Robert Downey, Jr. played Sherlock Holmes to perfection. His characteristic caustic attitude towards Lestrade and even Watson at times was exactly how I'd imagine him. He gives several summations of his observations and deductions that brought Holmes to life in an almost unparalleled way. His fight scenes (preceded the first few times by superhuman calculations) show both the mental and physical sides of Holmes in ways that Watson's notes can't quite convey, but at which they constantly hint.
As for Watson himself, Jude Law delivered a wonderful performance. I was a little skeptical of how well he fought, given Watson's wartime injury, but his character and demeanor were entirely on the nose. His loyalty to Holmes despite his frustrations with him could not have been captured more expertly, I feel. No one, no matter how patient or forgiving, could endure Holmes forever without the occasional confrontation. The original Holmes, after all, was not above insulting his best friend or even deriding his deductive capabilities at times. Nevertheless, Watson never could abandon his friend in his time of need.
This version (or vision, if you will) of Sir Arthur Conan Doyle's greatest creation may be more swashbuckling, more thrilling, and more edgy than any other incarnation, but that doesn't make it any less faithful to the original. Aside from a little revisionist history in the cases of the female leads, nothing is that far out of the ordinary; and no amount of references to Madonna will change that.