Alright, I’m late to the party but I wanted to toss up an opinion. (Feel free to disagree!)
I liked season three, for a few reasons. While it’s true I don’t think ep1 will age very well, it had to do a lot of work. It needed to explain, without too much detail, what Sherlock did for his absence… what John got up to and where the rest of the Sherlock characters were/what they were doing. The case didn’t get a lot of attention, because the show is about a detective… it never promised to be a formulaic crime-show.
Another reason I fell kind of hard for season three? We get a season from Sherlock’s perspective. It changes the feel of the show because previously we tended to get John’s perspective. (We get loads more screentime where Sherlock is doing Sherlock-y things… and we get to see the inside of his mind palace.)
“So?” You say,”We got to see the mind palace in Hound of Baskerville.” Maybe. But it’s evolved since then. A lot.
*End tangent.*