I can't say I loved the ending, but I clearly didn't hate it. I accepted it, I accepted the death of Rachel and all the bad stuff. I'd prefer if Katherine wrote a longer ending, explaining more about what happened after the end of the war... But I always accepted her choices.
I think writing the end of a novel or a serie is the hardest thing, because there'll be somebody, at least one person, who will totally disagree with it. But what you said is right, Nohensen: she stayed true with her heart ^^
Same for Remnants' end. The saddest is that wouldn't be true for Everworld, if she stopped because it wasn't a big success, as I heard...