Couldn't agree more that what we’ve been seeing throughout Season 2-3 has been A) boring, esoteric and worse, convoluted crime plots with lack of stakes, too little action and way, way too much statically shot exposition B) Watson continually shortchanged in terms of character / emotional development C) promising backstory threads introduced and immediately dropped (Joan's family, Gregson's wife/daughter, etc.) D) huge chunks of key emotional stories happening off screen and E) the absence of worthy adversaries (I know Moriarty/Natalie Dormer is busy, but doesn't she have any minions available to do her dirty work?).
As for the finale, the decision itself to kick Sherlock off the wagon works fine for me. He's always hanging onto his sobriety by a thread. My beef is the way in which that thread was cut. He was pushed off the wagon, instead of falling off of it on his own, which would've made much more narrative sense and which they seemed to have been setting up all season.
And no doubt, JLM is wonderful and played the hell out of what he was given. But I do not buy for one millisecond that after spending two days with Oscar berating, hounding and manipulating him into using again, that the strong-willed, stubborn Sherlock would immediately turn around and give Oscar the satisfaction of getting exactly what he wanted. That trigger did not seem true to the character -- no trigger at all would've been a much more powerful statement on dealing with addiction. Plus, the ending was needlessly ambiguous -- it might've been interesting to speculate over the hiatus whether Holmes was upset over killing Oscar or whether he'd actually used. But then the showrunner comes out and says for sure he'd relapsed. If half your audience is confused about that, then you're doing something seriously wrong.
But the most gut-wrenching failure of the finale was depriving Watson -- his former sober companion, best friend and partner -- of the onscreen moment where she realizes that Sherlock has relapsed. This follows a mid-season climax in which Watson is leaning over her gasping-for-air boyfriend and then by the next episode, he's died, been buried and his freaking murderer has been caught -- all off screen.
This is a shocking waste of Lucy Liu's talent (save for her directing, which is excellent), not to mention the excellent chemistry between the leads. And it all points back to the failures in the writers' room. Please, Lord (AKA CBS) can we have a new showrunner, more than one woman writer, and MORE WATSON?
