So, Angel Sanctuary is an older series published by Viz here in North America and virtually out of print as of right now. You can still order copies although some volumes are really difficult to come by. The mystery behind the title doesn't become apparently until volume 19 when they refer to a place called Angel Sanctuary which is the island that the creator God lives on in the highest layer of Heaven. The whole story centers around a reincarnated female angel who is pushed into a new life in the body of a human boy. She loses her former consciousness and is now for all intents and purposes, a teenager names Setsuna Mudo. The forces of good and evil clash around him, and involve him in the centuries old far between heaven and hell. The best part for me with regards to the series, happens to be the blurred lines between good and evil. Many of the demons in Hell are well-meaning creatures, while many of the angels in Heaven are loathsome and selfish. They trample the innocent to further their own personal goals.
The story itself does not favor Heaven over Hell. In fact all characters are driven by their own desires and hurt others around them while trying to accomplish their goals. This appears to be the central theme of the story. Follow your heart but do so carefully or accept the consequences.
As for the ending, I was very please with how it wrapped up. I'm not one for super sappy, happy endings however, I felt that it was an appropriate ending for a story which contained so much carnage. I had to endure my favorite characters death twice in one book! That's pretty harsh. So the ending was suitable for me. Finding out how the angels were born was of particular interest to me. Make no mistake, I could most likely write an essay on the intricacies of this 20 volume manga. I just don't want to bore the crap out of anyone. I shall say this: Angel Sanctuary remains one of my favorite manga's of all time, that wasn't written by Osamu Tezuka. LOL I think that's a pretty significant compliment.