My verdict: The show is pretty engaging and the characters are interesting. Cumberpatch (who looks stereotypically British) delivers a Sherlock Holmes who is surprisingly fallible and petulant. And Dr. Watson is almost clingy. The third episode is easily the best and introduces Holmes' arch-nemesis. Jim Moriarty comes off as a bit fruity at first, but turns out to be a fantastic villain. He was almost surely informed by Heath Ledger's Joker in The Dark Knight. The music is well-suited to the show and catchy. One more thought: the title footage makes London look like a model train set and I wish I knew how they did it.
Tower Bridge is by Peter Trimming, available at http://commons.wikimedia.org/wiki/File:Tower Bridge at Sunset - geograph.org.uk - 1804231.jpg.