Saint Tail is a pleasant, light hearted series about a teenage girl, Meimi, who (between having a magician father and an ex/thief mother) disguises herself as Saint Tail to do good deeds, usually returning something that was wrongfully stolen to its rightful owner. She does this with the help of her best friend Seira, a nun in training.
Along the way, she manages to pick up the attention of Asuka Jr, a detectives son who is determined to catch her, originally for justice, then to just prove he can, and then for even more complicated reasons. Meimi finds herself developing a crush on Asuka, which complicates things, as she has to hide her secret identity.
Not an incredibly plausible premise, and perhaps not very original. But it is well executed, with entertaining characters and nice artwork. In order to stretch the plotline from the book series that it's based on, the animators decided to come up with more random things for her to steal, and more foolish mistakes for Asuka and the classmates to make. This can get rather repetitive, but the episodes that are directly pulled from the books are very well done, and the relationship between Meimi and Asuka is sweet and touching, as well as confusing and at times down right comical.
If you are into the kind of "magical girl" anime style, don't pass it up. If you're not a fan of that, it's probably not for you. I give it a 7.5 out of 10.