Just to be clear, I only saw the anime version, but I definitely recommend it. It is well-thought, with complex characters and plot lines that will keep you guessing. It's a very dark anime, for more mature audiences, but if you can deal with a little tragedy and horrific events, then you'll like it.
To me, this anime felt like an epic. After watching it through once, I felt completely satisfied. The only other time I felt like that was after seeing the end of the television show "Lost". All though it wasn't necessarily happy, everything was perfect the way it was, and that I wouldn't have changed it for anything.
One thing I loved about this anime is that it doesn't make fighting into a happy "let's improve ourselves and have fun while we're at it" sort of thing. Instead the fights gave a very realistic sense of tragedy and horror. This anime did a very good job of making you feel how you would have if you'd actually been there.
Character Development: 9.5/10
There is some great character development, especially with the main character, and her coming to accept who she is, and her best friend/adopted brother.
The best friend had perhaps some of the best character development I've ever seen. He goes from being an annoying whiny character that you really hate to someone who is dependable and really like able.
I remember reading somewhere when I was still watching the anime that he got to be a really great character, and I didn't believe because I disliked him so much and once I dislike a character, that usually doesn't ever change. But in this case, by the time the anime was over, he was one of my favorite characters.
Character Relationships: 10/10
These are very realistic. The characters have to make some very difficult decisions based on love, family, loyalty, etc., and it deals with the decisions in a very touching and realistic way. In this anime, there are no easy answers.
Plot: 9.5/10
The plot is fantastic. It's very interesting, because the main character starts out with amnesia, so you aren't really sure what's going on at first anymore than she is, and you have to unlock the secrets of her past together.
Art: 10/10
Not much to say for that. It's really beautiful.
I was going to give this an overall grade of 9.8/10, but I realized that it's pretty much perfect, for what it is, and I can't give perfection anything less than a 10.
Overall: 10/10