I'm not sure what to think of this episode. It's certainly the most competent episode yet and, while the story felt like a flatter version of a great episode of Leverage, it had the fewest goofs, dumb moments and a plot that just about makes sense.
I found the story serviceable but just a day later I'm having trouble remembering the details but I know I enjoyed it at the time and it avoided the obvious twists... it even felt like they setup some traps for the viewer to make guesses at the eventual outcome and then introduced a final twist that, while pretty basic, was effective.
The sub plot of Watson's family was somewhat redundant but it was nice to see Sherlock being something other than a pain in Watson's neck. It's small character developments like that that the shows been missing and almost feel like a deliberate attempt to differentiate between Sherlock and the titular House whose show this one often mirrors.
Finally getting the pay off after so many episodes has been rather a painful experience but still am glad I stuck around this long to see where the show could be going.