The Long Answer.
I enjoy the characters, but saying I watch Sherlock for the characters is like when Soderbergh said people would like Ocean's 12 because they don't care about the heist. The Mystery of episode 1 is vague, poor and undeveloped. You could argue the mystery is how Sherlock survived the fall, but again that's only vaguely handled. That I can't tell you about the main mystery - something involving a bomb - is a major weakness of the show, existing solely in THIS episode.
The visual style is also a poor copy of the first 2 Seasons, with a scene in the train station that contains the worst shots of the series.
Sherlock: A Scandal in Belgravia is my new #62 film of All Time.
For some this particular Sherlock is too much of a good thing. The multiple narratives use some very clever technical tricks. (Too clever?) One of my favorites is the case Holmes solves while unconscious. As he reaches the solution in the middle of a grassy field, a bed rises into frame to catch him. There's a lot of text on screen, Watson's blog posts, a strong hint that Holmes may be a recovering addict, and lots more than make this a ride I want to take again and again.