For anyone who hasn't yet watched the series-

NANA is definitely one of my favorite anime series. If you enjoy real life drama shows, then this series is probably something you would like. If you are in the anime genre for Mecha, Magic, Fan Service, or generally more light hearted or fantastical series then this is not something you will probably enjoy.

Most of the story lines center around relationships, emotions, life hardships, and similar things. Though there is plenty in the anime that is very funny and entertaining as well. I very much enjoy the characters for their realism. There isn't a Mary Sue in this series. Every character has a history that is believable, and personalities that have both good and bad qualities. They and the situations they find themselves in, despite possibly a little out there... obviously most people aren't famous and have a record deal, but they are close enough to real life to be empathized with.

The movies are good, but I felt (as I feel with all Anime movies) that everything was a bit rushed.

NANA the movies, Manga, and NANA the anime series are licensed now in the United States by Viz Media. The movies have been produced and subtitled in English and if are not available, then should be available quite soon. The Anime, though licensed, the company who bought the title for English release have yet to say anything on a date of production. If you computer is fast enough members of Youtube.com have uploaded the complete series subtitled in English.

The music, as other posters have mentioned, is quite good. Anna Tsuchiya and Olivia Lufkin's voice talents are amazing. Here are the titles, most can be downloaded from Gendou.com or from Livewire.

Theme songs

* Openings

1. "Rose" by Anna inspired by Nana (Black Stones)
2. "Wish" by Olivia inspired by Reira (Trapnest)
3. "Lucy" by Anna Tsuchiya inspired by Nana (Black Stones)

* Endings

1. "a little pain" by Olivia inspired by Reira (Trapnest)
2. "Starless Night" by Olivia inspi' Reira (Trapnest)
3. "Kuroi Namida" (黒い涙) by Anna Tsuchiya inspired by Nana (Black Stones)
4. "Winter sleep" by Olivia inspired by Reira (Trapnest)
5. "stand by me" by Anna Tsuchiya inspired by Nana (Black Stones)

* Inserts

1. "Zero" by Anna Tsuchiya inspired by Nana (Black Stones) (First played in Episode 4, also played in episodes 5, 10, 19, 30, and 39).
2. "Recorded Butterflies" by Olivia inspired by Reira (Trapnest) (First played in Episode 18, also played in episodes 22 and 27).
3. "Shadow of Love" by Olivia inspired by Reira (Trapnest) (Instrumental version first played in Episode 32, also played in episodes 34, 35, 37, 39, 41, 42, and 44. Vocal version first played in Episode 45)

(taken from the Nana wikipedia article)

Hopefully more people will enjoy this anime as I have. ^^