I have conflicted relationship with this webtoon. It starts slowly, and then the pacing is weird - at times it drags: there were threads that in retrospect didn't go anywhere, and characters introduced, that didn't have that much point to them ; build ups for significant things are "hidden" among other stuff, so if you're not paying attention, they may catch you out of nowhere. Or give an impression of writing being all over the place, to which there might be something to (especially in the first half).
I wanted to abandon it several times, but in the end wasn't able to (though it took me quite a long time to finish). The "mystery" part of the story was good (as good as it gets in character driven plots anyway ; it all started coming together in the last twenty chapters or so), "comedy" was hit and miss (but when it was a "miss", it wasn't awful or cringy), and "romance" turned out to be really sweet and natural in the end. Art improved significantly throughout course of the story, and although it never went above certain level of aesthetic refinement, there were several panels that struck me as beautiful (be it because of the coloring, their emotional significance, general ambiance of the scene or mix of those, i don't know). All those merits aside, "Pinocchio"'s still uneven and at times naive - such are the charms of works penned by inexperienced young authors (similar case can be made for "Nanohana boys", although miss Pyon's tale feels much more concise). For what it's worth, i think the main plot points and it's conclusion were planned from the very start, but it took too many (seemingly insignificant) detours for the story to hit them. It was a learning experience for the artist, and at times it shows.
All in all, i'm not sure whether "Pinocchio" is good title to recommend to. I'm happy that i got to finish it, and that i got to know the characters, but whether you'll like the non-amateurish-nor-quite-professional vibe that it gives, depends very much on individual taste. I don't want to praise it or put it down too much, so let me end my rant with this: if i recall correctly, it used to be REALLY popular three or four years ago, and i can see both the reasons behind that popularity, and think of ones why it surprises me. If you're a "shoujo with gimmicks" lover, or if you try to read it in smaller doses (instead of trying to binge it, like i did several times), you'll probably enjoy it, but then again, chances are you won't.