But that last episode was the best Sherlock episode there has been, by far.
To be fair, it wasn't really much like a typical Sherlock episode. Solving the mystery of "who committed this crime" was not the central plot, but then, that hasn't been the plot of an episode since S3E2, so Sherlock has already gone fairly meta. This didn't just go meta (like the terrible tumblr-bating of S3E1) but dealt with its themes in an intelligent way making use of imagery and character archetypes.
This is a bit like saying that Majora's Mask was the best Zelda game. Or praising the extremely controversial adaptation of Murder on the Orient Express in the David Suchet series. They're so good that you have to admit they aren't in keeping with the rest of the franchise, but are better for departing from it.
Sadly few of you have seen it. Maybe look into that. But today this blog is mostly going to criticize the terrible school of review that mis-judges episodes like this so badly.
Witness, the Onion AV Club review. "A borderline incoherent episode still manages to shine, thanks to the occasional dazzling moment"
Sigh. Thanks for letting us know its incoherent, but what is it saying?
Last, while the episode contains more visual clunkers than the average Sherlock outing—that Mycroft scare sequence is only unsettling for the briefest of moments, and the explosion of 221B has to be the single worst visual effect the show has ever filmed—it’s still a treat for the eyes, particularly the moment in which the walls of Sherlock’s prison fall away to reveal Musgrave. It’s worth the ridiculous notion that Sherlock would fail to notice the lack of glass between he and his sister for the breathtaking moment in which their hands meet, and the show’s familiar perspective-altering pans and falls remain surprising and unnerving.
Right, the episode has an extended interrogation scene where Sherlock stands opposite his sociopathic sister. She's in jail, he's the most respected detective in the world, and nothing like her. All that separates them is an impenetrable barrier of bulletproof glass, but that glass is the most important line in the world.
Except the glass doesn't exist at all and there's nothing dividing them.
You don't need a degree in literature to analyze this metaphor. It's not a "ridiculous notion", it's the entire damn point of the episode. (Including that Sherlock fails to notice things when his emotions distract him.) "You and I aren't so different; in fact were the same," represented with an optical illusion - that climaxes with the breathtaking shot of her grabbing his hand.
The symbolism in this episode is not subtle in the slightest. Even Sherlock does some literary interpretation, noting that his sister imagines herself on an airplane, because she is "so far above everyone" and she's calling him because he's the only one who can hear her. She plays with a toy plane throughout.
Sherlock must solve a series of puzzles accompanied by only Mycroft and Watson. They are referred to as representing his intellect and his heart repeatedly, but also his family and his friend. Every line of dialogue he has with them in that dungeon builds on these dichotomies, making it an effective character study of himself. (When forced to choose who lives, his "brain" sneeringly commands Sherlock to shoot the "heart", hoping to make killing the brain easier on him. Once the charade is uncovered, the brain/Mycroft still insists on himself being shot, but "don't shoot me in the head, shoot me in the heart.")
This is a very well written episode.
And for god's sake don't take the things said and done purely literally. What the hell is AV Club doing complaining about over complicated plot devices in an episode of Sherlock. As they acknowledge, the core of the plot is pretty simple, so just watch the thematic elements interact beautifully.
Something Eurus says herself when she declares, there never was a bomb in Molly's apartment, just two people emotionally tearing into each other.