I don't know how to start this review, because Fruits Basket is very special to me, and I don't want to seem overly harsh. So, let me clarify--the structural story, characters, and development of Fruits Basket is defined by the manga. The anime took severe liberties and shifted the entire focus to a far less poignant theme.
The beauty of FB reminds me of a flower bud, slowly opening. Each character is a thousand layers deep, and things you thought you understood at first glance are proven far different later on. Tohru annoyed the crap out of me at first, but as the series progressed, I grew to love her and want the best for her (much like the protective spirit of her gangster and psychic friends).
Let me warn you, though--if you've read the manga, and treasured the profound sense of closure that the last volumes brought, you will be severely disappointed and upset by the way they wrap up the anime. I honestly felt angry and cheated.