Under a cut for minor spoilers (I suppose)--nothing too major, but I'd recommend going into the episode cold to preserve the suspense. A more in-depth reaction will likely come once I've rewatched the episode a time or two more later in the week.
I’m a bit mixed, honestly. On the one hand, I loved it. There was much more development than I expected of the minor characters-substantial amounts for Mycroft, Mrs. Hudson, a bit for Molly, and though we didn’t see too much of Lestrade, there was the bit about his wife, which was nice. Sherlock’s protecting Mrs. Hudson was the sweetest thing ever and I love that they’re delving more into how much he really does care about the ones he loves. His and John’s dynamic is evolving, and I appreciated the cheeky references to canon in the opening sequence. I am, though, truly sad to hear that Sarah’s gone. How they got out of the pool was, admittedly, a bit of a copout, but let’s face it, there weren’t very many resolutions to that scenario that wouldn’t have been.
On the other hand, Moffat’s twisted ideas about gender continue to annoy me, and I’m continually irritated about how Irene is treated in the adaptations. Nothing was consummated here, but why does their dynamic have to be sexual in this and the Ritchie film? Sherlock doesn’t reciprocate here, but the flirting and such got to be a bit much. Yes, it makes sense that a modern day Irene would use her body to get what she wants, but is it too much to ask that she not fall into the common stereotype of the seductress? She can’t just be brilliant in her own right, instead of “look at me, I have breasts that can distract you, and by the way my measurements are my safe code”? Did the chime for Sherlock’s phone really have to be an orgasm? She was smart, clearly, but I felt like all that intelligence was undermined by the focus on her body. Maybe that was just me. I guess it was kind of awesome that she chose to be a sex worker for her own sake (at least, we never saw any indication otherwise), but I wasn’t thrilled with the sexual angle when the original canon is extremely and explicitly clear that Holmes only admired her for her intellect, not for any sexual reason.
On a third-and most confusing-hand, I’m truly baffled by how Moffat, Cumberbatch, and Freeman keep insisting that though the subtext is there, there’s nothing to imply that Sherlock and John are or could be at some future point in a relationship. I’m sorry, it’s just being spelled out with flashing rainbow letters now. Jeannette said it to John herself-they are in a relationship. Jim said it, for God’s sake-John is Sherlock’s heart. Maybe it’s not strictly romantic (and trust me, I ship it, but I never want to see it happen in canon, and I’m not saying it should), but the subtext is there and if they want people to stop reading that way, they should stop putting it there…