awww. this is a very great adaptation. The scenes weren't cramped to fit in just two hours unlike other live actions. Such a sweet story where everything I want is happening haha! It's alright if you havent read the manga. You will still be able to feel it. The scenes are whole, I mean, they are connected to each other not just some different scenes put together which is for me, a bad habit of some japanese live actions.
If you try to put as much manga scenes as possible in a two-hour movie, it would definitely be cramped. I liked that this movie focused on one arc then combined it with the last arc (they left out a lot of scenes/arc from the manga but it's one of the reasons i liked this movie). It will make more sense to those who havent read the manga yet. It's like a stand alone movie, with or without the manga, you will still like it!
If you want to see and read more ItoXShimada scenes, then read the manga! hehe.

btw, Ikuta Toma and Hirose Suzu has a 14-year age gap and that struck me hard! Awesome! Sugoi! XD