I bought this game the day it came out (as well as Itadaki Street DS) and I adore it. It is a life sim where basically you're a girl who's moved to Tokyo and you meet the Nana characters. You have three months to build your skills and make friends with the characters so you can get offered a job in the entourage of either Blast or Trapnest.
There's a lot of replay value, and a nice bonus is after you've beaten it once, you can play again and still keep most of the items (ex. clothing, hairstyles, etc) you bought in previous games.