Not the worst Holmes movie that I have ever seen (I reserve that for The Adventure of Sherlock Holmes' Smarter Brother (1975) directed and starring Gene Wilder), and a trifle better than Without a Clue - which is to say, it was still really, really bad.

It was a step up from the treatment of Wild, Wild West, and had decent sets. Downey as Holmes annoyed the Hell out of me, but Jude Law was better as Watson than I expected. Both could have worked on their diction, and taken a little note of Victorian sensibilities.
I would give it a 2.5 out of the 10 above. But, I didn't have to pay for it, so I'll live.

Plot was not so much convoluted as lost, but Doyle was guilty of that too, more than once. What I really did not like was the interaction between Holmes and Watson - it grated like sand in the gear box.
Brett remains the best Holmes, so far. If Jude Law had the diction a trifle closer he might be the best Watson, even though the movie itself is really not all that good. It did make me want to see a steampunk Sherlock movie sometime, though.
The Auld Grump, for that matter, I would like to see the Holmes & Russel series by Laurie R. King become a movie series....