If you saw the anime, sometime after chapter 40 you will notice A LOT of different things going on in the manga. The anime is a more "light" version of this story, it doesn't go very deep or get an inch of the complexities that the characters go through in the manga.
I liked the anime, it was hopeful, yet bittersweet. I love the manga, it's tragic and holds your heart hostage keeping you hoping for a sliver of llight that perhaps the pain you've been burdened with with get better... then 20 chapters later you're slapped with the cold hard truth that shattered your hopes. But somehow, you feel at peace.
I cried so much around chapter 50, and then I cried so much more after chapter 70. But the second time it felt more like a relief, at least my heart was set free, no longer hostage toying with my feelings.
At least Yoite was not in vain.
Nabari no Ou