I have to place my two pennies worth regarding this series and it's art style.
Many people here have been saying that this series style is going for an "ultra-realistic" approach however, those that do say this have fallen into the trap, psychologically that is.
If you take a close look at the drawing, you'll note that many scenes and the characters themselves are outlined however when you then look at features and colour, the artists have used modern art techniques and one would class the art style as "impressionist". The only features that are clearly detailed, are physical proportions and anything that must be detailed such as signs, posters, books, anything with writing etc. Take a look at the anime, look at the trees, look at the houses, you'll notice that there isn't actually any detail.
Now I've watched all the episodes so far and it's brilliant so far, the dialogue, the scenes, the music and the overall atmosphere are compelling and believable and this is why I also understand this art style as being impressionist art.
You'll not that in my 2nd paragraph, I spoke that people fell into a trap, well, the reason being is, the authors and artists want you to be immersed into the story, they've made you think and believe that it's hyper real. It shows through in the animation as well, if it was going to be hyper realistic, the animation would be smooth and accurate but several times we see characters who move along, while frames may be missing, they move in proportions to how one would normally move. This is probably one element within the animation that is realistic, but again that's in terms of proportions used as thanks to the technique of rotoscoping, our minds fill in the rest.
I really have to give the production staff a lot of credit, this is really clever and top quality, I'm really impressed with it. As such, I can't wait to see what crazy Nakamura does next although I wish Kasuga would stop being such a wimp and grow some balls.
After all that I'm suddenly remembering the cross-study I did back in school in Art and English Literature about Alfred Hitchcock and critically analysing his work.