they're playing a bit of a dangerous game by making Sherlock so thoroughly unsympathetic and unlikable -- there needs to be a payoff here; you can only do the "Is Batman as bad as the criminals he fights?" theme for so long without reminding the audience that the answer is in fact "No."
Payoff achieved, in an episode that revolves entirely around Sherlock caring about people, in his own damaged way. And yes, the climax revolves entirely around him casually asserting that caring about people is stupid and makes you sloppy (well, that and a pun that made me literally groan), but his actions throughout the rest of the episode suggest otherwise.
Really some wonderful Moffat dialogue, and a great version of Miss Adler. A couple of weaknesses, the biggest of which is the MacGuffin. The show, up to this point, has done a brilliant job of bringing a Victorian series into the twenty-first century, but this time we have an episode that relies fundamentally on a twentieth-century conception of technology. Moffat can handwave all he wants to try and make it plausible that there's a cellphone with important data stored locally on it, no backups anywhere, and no way to retrieve that data outside of correctly typing in a passcode within a set number of tries, but it's stupid. Honestly it would have made more sense just to make it a briefcase full of negatives and spend all that handwaving on explaining why she'd be carrying around a briefcase or using film.
(Also, fridge logic time: [spoiler]Even allowing for a phone that uses a 4-digit, case-insensitive alphanumeric passcode, what if she'd spelled it "sure" instead of "sher"? Pun still works -- arguably better, even -- and Holmes is left with a phone full of melted hard drives. Because phones have hard drives.[/spoiler])
Those technical quibbles aside (and [spoiler]the far-too-quick resolution of last season's cliffhanger -- though the Stayin' Alive ringtone was a nice touch[/spoiler]), it was pretty excellent. Indeed, even the 90-minute runtime worked well in this one, not least because of the three clearly-defined acts.
Next week: Hounds of Baskerville. Looking forward to it.