There is a very specific reason why Daughter of 20 Faces doesn't work. However to properly explain this point, I have to spoil pretty much the entire plot. Bear with me though, because it's a damn good point.
Daughter of 20 Faces is a Bones anime from spring 2008. The story is about a girl called Chieko who was freed from her horrible life with her evil stepmother by a band of thieves led by the charismatic 20 Faces. The band became Chieko’s surrogate family, with 20 Faces become a father figure to her. He taught Chieko tricks of the trade along with many other lessons about humanity and morals and so on. Chieko was a pretty talented thief in her own right even at a young age, many suggesting she would succeed 20 Faces to be the new leader. She became the ‘daughter of 20 faces’ so to say. That is, until shit got real in episode 6. I can’t quite remember the exact details, but basically 20 Faces rescued Chieko and disappeared off on a burning train, presumably to have died.
This is the Death of the Tutor, a pretty standard trope in any mode of story-telling. Everything from Star Wars to Madoka Magica does this. The reason it happens is to allow for further development of the main character. They learn the life lessons from the tutor but they can’t move on while they live in the shadow of said tutor. The Death of the Tutor shocks them out of that sense of security and forces them to develop themselves. This is exactly what happens in Daughter of 20 Faces. Chieko’s development went from talented child under her evil stepmother to finally having the freedom and guidance to train these talents of her. Getting 20 Faces out the picture forced Chieko to develop further. There was some moping but she then went on to form the ‘detective girls’ with some friends, starting down the road of a perhaps more law-abiding version of 20 Faces gang of thieves. They discover a bigger plot is going on, Chieko and co. start to uncover the mystery until about episode 12 where the fatal happens.
20 Faces comes back.
And with that, the story dies.
Chieko reverts back to how she was before episode 6. Her development is aborted. She’s back to relying on 20 Faces for guidance, unable to tackle these problems herself. The ‘plot’ continues, but the plot was never particularly good to begin with. It was a vague mystical science thing where water can blow up, scary scientists plot world domination and plot holes are as regular as a panty flash in Rosario to Vampire. The real appeal of the anime lay in the development of Chieko’s character, which until now had been done brilliantly. That ended with 20 Faces return. She wasn’t capable of developing further.The author didn’t have the balls to kill off 20 Faces, but in bringing him back, he succeeded in killing his very own story. The Death of the Tutor seems like a tired trope, but watching Daughter of 20 Faces brought to light how important it truly is.
Since this is MAL, you're apparently meant to cover points like animation and sound even when they have nothing to do with the points you are making. So here we go:
Story: Plot is as dumb as fuck. The real story ends in episode 12
Art: Good. This is still Bones after all
Sound: Forgettable. Lots of Aya Hirano going 'Oji-san'
Character: See entire above review
Enjoyment: Ended when 20 Faces came back