You know, I really like this show. I really do. Last week's episode was awesome. I would never deny that. But I have to say that this season finale, 'The Final Problem', kind of takes the shine off the whole season, if not the entire series.
It's not that it is bad, especially by the standard of current network television, but at several points it just kind of careens off into being an episode of something sort of good that also isn't necessarily an episode of 'Sherlock'.
To wit, this wouldn't be a bad episode of, say, an anthology series based on 'Saw' (if there were an anthology series based on 'Saw'). It wouldn't be a bad episode of some suspenseful high-tension drama show like 'Hannibal', where people pursue a serial killer, and have to face some traumatic personal and emotional challenges. It's not even a terrible level of 'Batman: Arkham Asylum', if you want to look at it that way. But what 'The Final Problem' is, at it's core, is by no means a good episode of 'Sherlock'.
Yes, this series does demand a certain level of suspension of disbelief to really be enjoyable, but some of the overly-complicated stuff in this episode is really quite unforgivably unhinged from reality. Let me quickly demonstrate how tenuous a grasp on the rational this episode has:
Near the end of the episode, Sherlock's parents discover that Mycroft has been lying to them about the fact that their daughter Eurus is actually still alive. And, being good, caring parents, they lose their minds and are outraged at the deception. Except, if you think about it, they themselves have obviously been willing accomplices in Mycroft's life-long deception of Sherlock. They actively cooperated with a scheme to prevent Sherock from remembering that Eurus ever existed! How can they judge Mycroft for something they have been willing to do with Sherlock? In fact, they are functionally twice as bad, because they've been lying to Sherlock about Eurus and Victor.
Just tugging on that one logical thread makes the whole thing collapse. And there are a lot of loose threads in this episode. This can be a real problem when you know that your series is being watched by a bunch of obsessive thread-tuggers.
But, really, the biggest issue with this episode is the ending. It wraps up way too quickly, and it does so in a manner that really doesn't make any contextual sense. We are to believe that Sherlock "finding" Eurus "alone on the plane" and being willing to "play with her" is enough to convince her to shut down her complex, life-long, murderous head games? Except Eurus is supposed to be, like Sherlock, a high-functioning sociopath, so any emotional appeal like this should fall on deaf ears. A cold-hearted, institutionalized sociopath lady who mentally manipulates people into murder (and who kills Governor's wives in cold blood) should probably not find herself utterly shattered by a brotherly Sherlock hug.
Anyway, I will try to forego my lengthy point-form deconstructions, but I did have to mention the following: