tl;dr Did you like the first movie? If so, go see it, if not, don't. Simples.
The most recent spate of adaptations of Conan Doyle's iconic detective was always going to be a rather unusual affair, what with the way it keeps the setting and styles of the book's original context, whilst bringing highly Hollywood action blockbuster sensibilities to the table. But between Guy Richie and Robert Downie Jr., this is a film series with an incredibly strong sense of character.
In this, the second outing in the series, we see our inimitable Mr Holmes go up against the shadowy figure from the first film, his arch nemesis: Moriarty. Meanwhile, Watson is getting ready to marry, and talks about stopping his crime-busting partnership with Holmes. As the two chase down Moriarty we meet Sherlock's brother Mycroft, French gypsies and German bomb factories. Moriarty has plans - evil plans - and it's up to our mismatched couple to save the day. Can you tell I dislike summarising films?
Anyway, this second installment runs with a very simple philosophy: if it ain't broke, don't fix it. We get more action, more explosions, more audacity and a plot convoluted enough to become enjoyable through it's innate silliness. With a tongue firmly in cheek and a disregard for any loftier ambitions than just entertaining the hell out of you, the second film is perhaps even an improvement on the first.
Character wise, there's certainly nothing new going on here. Holmes is as flamboyant and silly as ever, hyper-articulate and incredibly observant. Watson is still proper, upright and socially more concious than his erstwhile friend. Their passive-aggressive need for each other is still as fun as it was the first time around. The treatment of female characters here is far from stellar; the film isn't sexist, but it clearly isn't particularly interested in them either. The biggest success of the pool of characters here was Stephen Fry's Mycroft Holmes, whose comic relief is always a welcome addition to the story rather than a tone disrupting annoyance.
As a villain I found Moriarty to be a fun and well executed Hollywood villain who was a little bit blander than I feel one of the most iconic criminal masterminds in literature deserved. He was not as interesting or as fun as his counterpart in Holmes. This, perhaps, was part of the point - to make him far more straight laced and academic than the off-beat Holmes, but the result came out a little too beige.
There's an irresistible energy to everything about this film, the way it shudders along like a train that is about to go off the rails. Richie's direction is sharp and, as already mentioned, helps to lend the flick a distinctive flavour. With a tight, funny script and tactical use of slow motion and flash forwards, this is a not inconsiderable film. The music is incredibly good too, Zimmerman turning in a score that has grandeur and excitement and more than little cheesiness mixed in.
There's lots of nitpicks to be had here: the female chars aren't well done, the plot is silly, Moriarty is a touch too bland. These are most definitely nitpicks however - this is a polished and highly enjoyable film that offers something a bit more colourful than most other action blockbusters out there. D'you like the last one? Really, that's the only question that you need to answer when deciding whether or not to see this movie.