I gotta say, I've read the manga. And - if I remember correctly - the very first scene of the film, aka the funeral, actually happened just at the end. So from the very first minutes the film caught me off guard a bit.
But overall... it was good, I think? I really liked the animation - it was truly brilliant. The music, on the other hand, was just good. Nothing too fancy, but it did its job
It was very cliché, but I enjoyed it, from start to finish. I actually teared up a bit during the most emotional scenes. Most of the film was pretty okay, but it was very varying level of okay. I liked Sakura's character, even though she'd probably annoy me if I were near her in real life. I think that her potrayal was rather... far from how real person with an illness would act, but hey, everyone does something different to cope.
Haruki, on the other hand, was extremely annoying at first. But I actually liked him, in the end. He had good character development.
Overall, I enjoyed it although out of all anime films I've ever watched, this won't top things like Paprika or Koe no Katachi. I'd say it's in the middle of my list