(Spoilers for said spot, and possibly the special, follow.)
It's amazing, really. Team Mofftiss have a world-class talent for actually giving us sizeable bits of content without acually giving us much at all. the style makes me cringe a little bit, and it feels wrong in the same way those first few scenes of "Hearse" did (I know I can't be the only one who breathed a sigh of relief when they cut off to Anderson and Greg). In a lot of ways, it's the natural progression of "Hearse" being so self-aware and intentionally trope-y.
But it's really interesting, too, once you get past all that. It's so obviously a fusion of modern and Victorian times, and if the special continues with that, I dont think we need to worry about it just being Benedict and Martin playing at a totally different Holmes. I've always hoped it would be some kind of meta commentary on the show, and I think there's something here to encourage that home. On the other hand, it could just be trying to grab the show's audience and get them interested in the new setting.
There's also so much to make me think they'll be playing with Sherlock's backstory, his family. The crime they're investigating is the dismemberment of a country squire, and if you know your Holmes canon, you know that's what the Holmes parents were. Which calls to mind the "other one," which in the Holmes 'verse (though not the stories themselves) is Sherrinford, the supposed third son who's supposed to relieve Mycroft and Sherlock of familial duties. A missing other one, a murdered one, could be very interesting - does that mean familial duties will come crashing down on Sherlock and, we can only hope, Mycroft? And then there's Archie who's always seemed like such a stand-in for young Sherlock (Sherlock fixing that childhood trauma of solving a murder and not having anyone willing to listen with him) the going "cool!" at maggots, the being isolated and disconnected from others, even the physical look. love Archie in any event and am glad to see him given such prominence here. And then of course there's "the one with the dog" which literally is almost certainly Hound but also screams Redbeard.
This could be a bit of fun, of course, and mean precisely nothing. Then again: Mofftiss Mofftiss...