I actually figured out most of Sherlock fairly early, though I was expecting the cause of the fear to be some sort of infrasound weapon, not a toxin. The rabbit was a bit of a give-away that evil science was afoot - those luminous genes don't come cheap - the villain was a little too obvious, possibly I was remembering the original, and I had a vague sort of idea that HOUND would turn out to be an acronym for a weapon name, I just got wrong on the details. They ditched most of the signals / escaped prisoner / evil housekeeper part of the original story, which was probably a good move, and the real rationale for the "signals" was suitably silly.
Great fun throughout, and some classic moments, not least Sherlock's memory palace. And huge kudos for casting Russel Tovey (George the werewolf from Being Human) as the Hound's prey.