Pretty dissappointing episode I felt. No I take that back basically a complete dissappointment.
The case itself was interesting and the reveal was fine IF the episode had only been about the case. The time jumping didn't work, injecting moriaty in didn't work, and the reveal of the murderer felt off and way too preachy, espicaily since this was all in Sherlocks head. I don't see a scenario where the present day sherlock would come to that conclusion or think a version of himself would give that speech, it just doesn't fit him.
If it had all been set in the 1800s and moriarty wasn't involved and the women revealed themselves as the murderers and someone else gave that speech or parts of it, it would have been another great episode. But as is, I can't claim it is anything but bad in my eyes. Revealing Moriaty to be alive, then explaining he isn't (Which I am not even sold on) in this time jumping psuedo mystery was quite possibly the worst way to go about doing things. A show that has had 9 absolutely fantastic, firing on all cylinder episodes in a row (IMO) to put out whatever you call this is prepostorous.
I liked the callbacks, but considering you are calling back to things at most 9 episodes ago isn't that big of a deal and at a certain point it simply seemed to become an episode devoted to fanservicing some subsection of their fanbase. If they wanted to make a connecting episode between seasons 3 and 4, don't do this. It could have been great, it honestly should've, with the interesting setup and the beautiful scenery. The acting was fine, but the writing killed whatever momentum the epsiode had going for it everytime it gained some and then threw a curveball that was utterly pointless.