The biggest issue with this manga is the extremely heavy-handed short-term foreshadowing. Without fail, before some big event happens the mangaka will make sure to spend multiple pages beating you over the head with what's coming. As an example, there is one particular double-page spread in chapter 1, clearly written to be the biggest dramatic moment of the chapter (and could have been a great one) that is undermined by the fact that instead of a gut-wrenching moment of "whoa, of course this was going to happen, but also wow" it's more like "yeah yeah everyone knows what's going to happen so let's just get it over with and move on with the story". This happens constantly, and really prevents the story from carrying the intended emotional weight.
Artwise, it's pretty good overall - nothing super special, but it has distinctive character art that works pretty well for the intended tone. It kind of devolves as it goes on though, starting out pretty competent but becoming increasingly poor near the end of the manga.
Aside from that, the pacing is good at the beginning but becomes weaker as it goes on. The character writing is fine, but a little shallow - the characters have a tendency to lack anything more than their rough outlines. I could critique the dialogue - there is a strong tendency for child characters to speak like caricatures of worldly adults, almost to the point of parody - but it is also entirely possible that this is a translation artifact, so I will not judge the manga on this basis.
Despite my issues with it, I think the manga was a worthwhile read, because failing in interesting ways is far superior to just being generically dull. I'll definitely be keeping an eye on the mangaka, because they are really just a few problems away from being excellent - I am reminded of Yukimura, for whom I rated Planetes a 5/10 as well but loved Vinland Saga.
