Sherlock Holmes lives in present-day Japan. He hangs out in Kabukicho, a famous Tokyo red light district, and solves crimes while doing rakugo stand-up comedy performances. (Actually, you sit down for rakugo, but never mind.)
At the start, I was all for this. It looked like a laugh. It's full of unconventional spins on the Conan Doyle canon. Unfortunately, though, my enthusiasm only lasted for about six episodes. They've changed so much (usually for the worse) that it's self-defeating to slap on Sherlock Holmes's name. If you changed the names and nothing else, no one would realise that it wasn't an original work. As it stands, though, by the end I was flipping through episodes in a disinterested way and wishing I was watching a proper adaptation.
SHERLOCK HOLMES (i.e. the title character)
...is the biggest hole in the show. I could forgive everything else, but there's very little about this guy that says "Sherlock". He's not actually interested in being a detective. (He's really a rakugo fanboy.) He's clever, yes, some of the time, eventually, but he doesn't show off with throwaway Holmesian deductions and the show feels the need to dress up his exposition as rakugo routines. He's just socially awkward. He has a tiresomely un-Sherlockian reaction to Irene Adler's cleavage (eps.8-9) and I was also annoyed by his reaction to Mycroft.
In other words, he's not Sherlock. He's a less compelling character of the same name with a few traits in common and a completely different backstory. Even the show's not that interested in him. It's got quite a large supporting cast, who'll often provide the protagonists of individual episodes. Sherlock might barely feature in those.
He's not that bad, though. I don't dislike him.
The show's use of Moriarty is probably its most interesting idea... or, rather, it had been, until the last few episodes. They lost me. On one level, this was inevitable and what we'd all been waiting for, given the character's adopted name, but they push it too far and I stopped caring.
Also, Sherlock's one of a team of detectives. Mrs Hudson (a cross-dressing gay man with a beard) runs an underground "Detective's Row House" where six detectives compete to be the first to crack the case and claim the reward. This creates a new dynamic for Sherlock and is quite a clever way of expanding the show's scope. Unfortunately, the rewards offered by their clients are so high that I didn't always believe that their clients could afford them, e.g. ep.5. That's a divorced mother with a child and not enough money, living hand to mouth. (That episode also has our heroes acting in what are clearly not the child's best interests. No one ever questions the mother's assumption that she's the one to look after the child, although it should be noted that Japan has unusual laws on divorce and child custody.)
OTHER ADAPTATION CHOICES
They have an excellent Watson, who's the real hero of the series, not Sherlock. Mrs Hudson is distinctive. Moriarty's interesting for most of the show.
On the other hand, the Baker Street Irregulars are repellent little shits. It's clearly deliberate that they've been loaded up with unlikeable traits, e.g. that ugly, sneering face on getting a Christmas present from Santa in ep.20, but this has been taken so far that I wanted them dead.
Irene Adler I found uninteresting, for no good reason, although she does shake up the show's format.
They adapt specific Conan Doyle stories, but with so many changes that knowing the original is almost a handicap. The puzzles and clues will all be different, occasionally in ways that don't make sense. (Apparently you can't copy the data on Sebastian Moran's data stick. That's not how data works. If you can read it, you can write it again.) Their version of 'The Red-Headed League' (ep.2) is immediately recognisable and I liked how they sneaked 'The Dancing Men' under my notice (not telling which episode), but otherwise there's not much point in looking out for links.
What's wrong with everyone's noses? It's like they all ran into a wall. I love the theme song, though, in particular the delivery of Yoshie Nakano from Ego-Wrappin'.
In short, I struggled to engage with this show. The regular cast were suppressing my interest levels, while the investigations didn't grab me either. It's the kind of adaptation where you wish they'd hidden the fact that it's an adaptation. I probably still wouldn't have thought it was particularly good, but it really doesn't help to be comparing this with Conan Doyle's stories.