Seems like it really jumped the shark this time around. It's been getting progressively cheesier and cliche, especially with the garbage plotline with Mary, but at this point it's basically Sad Doctor Who. They treat the original Arthur Conan Doyle stories as jokes, essentially (the first episode had him solving dozens with single text messages). Mary's story gets even more unbelievable and uninteresting. The audience has no hope of solving the mystery with the characters, as it's a jumbled mess until it's solved in the last 5 minutes with a quick stream of exposition.
Episodes 1 and 2 are 4/10 so far. At least Martin Freeman is fun to watch.