This is a live version adaptation of the popular Manga and Anime series about the lives of two girls both named Nana. This movie focuses more on the singer Nana Osaki, followed by a sequel which is mainly about the other Nana.
Having watched the anime beforehand (around 40 episodes.) , I must say the live adaptation somewhat had me disappointed. Despite reasonable performances by the cast, the emotional connectedness and character development over the course of the animation series appears simply rushed through in the movie and leaves you unfulfilled. Not to say music tracks in the Anime are simply superb. Due to health reasons, the author did not manage to fully complete the manga storyline, so Nana is as of yet an unfinished work.
Verdict: Before watching this, watch the anime, if you can, to really enjoy Nana. I for one am glad I did.