聲の形 is a deep story with the highest of high’s and low low’s. That being said I think it is the perfect length and a must read for those learning Japanese through reading manga.
The vocabulary has a lot to do with every day life. That being said there are also some low frequency words that the author uses often. I would see a word I didn’t know, only to look it up and see it’s a synonym of a word I did know.
The grammar isn’t too difficult. I would recommend attaining an n3. I attempted this
Great arc
Takes place in the best arc in the whole story. Some hard vocabulary but if you watched naruto with sub as a kid before starting to learn Japanese, (like I did) then you should be able to enjoy it with out too much difficulty.