Sherlock Who?
It's true that a few lines of the dialog were quotes from the original Holmes stories... but these were actually somewhat jarring, as the rest of the movie was pretty much made up out of thin air. It's obvious that there was no real attempt to capture the essence of Sherlock Holmes, much less capture the flavor of Conan Doyle's writings.
This movie could've featured some other fictional protagonist, and aside from those few quotes I mentioned, nothing would've needed to change except for the names. Of course, then they couldn't draw upon the name Sherlock Holmes to rake in more money, could they?
Go see this movie if you're interested, just don't expect it to be a Sherlock Holmes movie. It isn't. You'll probably enjoy it just fine; the problem, however, is that this generation of moviegoers is likely to come away with a really distorted view of Sherlock Holmes-- and given how great a literary character he is, that's a real shame.