If you're expecting the cutesy girl's anime that everyone has so come to recognize from a title like this, you're only half correct. Princess Nine is a story of growing up and surviving high school--and all the drama that goes along with it.
Each of the nine girls get their time in the spotlight and yet each of them retain some flatness. There simply were not enough episodes for full characterization. However! Each of the characters were lovable in her own way, and that made the series that much more enjoyable. The storyline was somewhat compelling; I did find myself rooting for them in the end despite the predictability. Just glad to see that Ryo and Takasugi finally got together.
Pretty good in my opinion; 9/10.