This anime holds a special place in my heart as it was one of the first ones I downloaded and watched.
I felt the ending was very nicely done. Saya goes back to sleep and her brother has decided to act as a father for her children. When she wakes up after her 30 year sleep, her brother would be old enough to be her father and the cycle continues. Haji is also implied to be alive; never really liked him but he would probably be the best to stay by Saya's side as they live through eternity. (or die somehow...)
The reason Diva is so strong is because she drinks blood freely whereas Saya only drinks enough to survive.
Why would you bash an anime just cos the dubs fail. Every single dubbed anime fails no exceptions, if anything you should be bashing yourself for watching this dubbed...