Ok so there are two things you should know going into this review. I used to read the Holmes stories over and over as a kid but haven't read them for a few years now.
Also, I love Robert Downey Junior and would cheerfully pay to watch him stare at himself in the mirror.
So it's stupid. The plot is outrageous, there are tonnes of intoxicating substances, some punch ups, some explosions and a very silly bit with a ship. Thing is, except for the explosions and the ship, it's pretty much how I remember the books. Punch ups, bad disguises, notes to Watson and send him of to do his bit on trust, mad logic leaps over insanely complex plots, a dead guy with red hair and just a joy. Sit back relax enjoy a ludicrous romp.