Okay. The series is based on some popular fantasy novels. Story is mainly centered around Yoko (red haired chick) who finds herself drawn from Japan to another world that has a bit of an ancient China feel to it. World is extremely detailed and well thought out.
She starts out as a generally unlikable character, whining and crying and feeling sorry for herself. As you watch her fight to survive in the country of Kou (one of the Twelve Kingdoms), her character matures a great deal and becomes far more agreeable. There are other stories later on, but if you don't like Yoko's story, you may as well not watch that far (45 episodes total).
Music is outstanding overall and lends the word a refreshing flavor. Animation is average to above average throughout the series.
Biggest downside is that the author stopped writing, and thus the series ends with many questions unanswered. There is an ending, and it's decent considering that they ran out of material, but it's still a bit unsatisfying.
Overall: It's awesome.