I feel like the setting isn't really being properly utilized, for one thing.
Most of Syd's deductions are shallow and half-assed (some of them aren't even actual deductions so much as solving word puzzles/ciphers). The bulk of the manga is also episodic zany antics that could just as well have been in any other romcom, rather than any real focus on mysteries or cases per se.
Which isn't to say that the wacky shenanigans are inherently an issue, in and of themselves, but what's the point of having Sherlock as your protagonist and the childhood friend as his Lestrade if they're hardly going to do any meaningful detective work? And I would love to interpret that as the manga simply knowing what it is and just taking the piss, but it's not as though the series is completely irreverent about its story, since it goes out of its way to have the Zero Craft plot as a recurring feature. It just doesn't dwell on any of the serious aspects long enough or in sufficient depth to be particularly interesting. About the closest it gets was on the cruise ship when some anons speculated about Zero actually being Souffle's split personality.