As weird as it sounds, I've never watched any Sherlock related movies or dramas and besides the fact that Sherlock solves cases along with Watson, I know nothing about it.
Having that said, here's what I thought of this drama:

The Good
(+) Sherlock, she's just awesome
(+) The interactions and tension between Sherlock and Wato are entertaining
(+) Wato's character. She's understandably mentally weak, but she's still kind and can be adorably naive
(+) Cases are entertaining
(+) Nice OST

The Bad
(-) Cases, even though entertaining, can be predictable
(-) Except Sherlock and Wato, the supporting cast don't have much personality to them, they're mostly just tools to move the plot forward.
(-) Somewhat weak main villain
(-) Questionable police work and investigation procedures

The Verdict
I enjoyed this show even though it has some flaws. Takeuchi Yuko did a good job with her character as Miss Sherlock. The investigations and line of reasoning aren't hard to follow so it can be watched leisurely. If you expect seemingly unsolvable cases or jaw-dropping plot twists, you'll be disappointed though.