That it is. If it were a 16 or 22 episode per season series the quality would inevitably drop--but it's a moot point anyway. Freeman and Cumberbatch are too much in demand elsewhere. It's fortunate that we're getting a series 3 and 4. The two stars genuinely like doing it. Neither one seems full of himself during interviews. They're both quite articulate. Strikingly so.
I have a favorite comedic scene from Sherlock as well. Hands down the best.