Storyline: It touched the plot in less than 5 episodes; rest of the ~20 episodes are fillers with little-if-any character development.
Characters: Protagonists are a disappointment. No character development in them. The male protagonist, Hiro, is useless throughout the whole series (minus ~1-2 episodes). The main villains rarely appear, and the ultimate one is not even revealed.
Animation+Music: Not too much, but nothing outstanding.
The manga's much better; I recommend that over this; unfortunately, I heard it's been discontinued at chapter 55.5 (I may be wrong here).
*And Princess Resurrection or Kaibutsu Oujo may be more appropriate titles.