I am not what you would call an anime freak, but i do enjoy a good series from time to time. I have waded through a lot of different shows and the only one I can compare this absolutely terrific series to is His and Her Circumstances (you will seriously wanna check that one out if you like this one, although that series revolves around a slightly younger group of people).
I started watching this show on a whim. I was bored one evening and start going through various shows here and happened upon this one. I almost didn't start the first show, but did in the end and I must say I do not regret it in the slightest. The character development and progression is well paced, giving you a sense that you are watching both main characters grow up before your eyes. The transition from childhood to adulthood is riveting and you will find yourself remembering emotions you may have felt in that period of your life as well. If you are a bit older, you will see what the people do and know that at that age you may have very well done the same thing.
The two main characters, both coincidently named Nana, are from completely different worlds. Nana K is a country girl from a small town who grew up in a two parent home, complete with two siblings. She is bright eyed and bushy tailed. However, as you will see, she is a bit conniving, secretive, and at times annoyingly whiny and selfish. Nana O on the other hand, is from a very broken home where she felt she was never wanted. She is cold and rigid, yet keeps a tough girl face on most of the time and hardly ever reveals who she is or how she feels.
The artwork at times is comical, but that only adds to the emotional transition of the characters; Very comic book like at times, then at others, extraordinarily real and quite beautiful. What sets this one aside from the cookie cutter anime you may have seen in the past is the sense of realism you get from the animation. The women are petite, but do not have ridiculously large breasts like you may have seen in other anime titles. This small but important detail adds to the credibility and down to earth feel of this series.
All in all, Nana is the best of both worlds. It's not afraid to be comical (at times it even pokes fun at the fact that it knows its just an animated show) and then completely flip to incredibly emotional, and at times, intensely romantic. The story telling and dialog are top shelf and in no way mask the feelings and emotions that a real woman may have. They do not hide the truth or conform in anyway to what most people would call standards.
If you skip this one over, you will never know just how great a story you have miss.