Let me put it this way:
When DRGIII's Plagues of Night/Raise the Dawn came out, a lot of people who had been down on Rough Beasts of Empire revised their opinion of that book.
I loved RBoE from the get-go, but did see this happen as well after PoN/RtD. It's one of those novels that truly work in a greater story.
I think that RBoE was supposed to be depressing and sad, so show that sometimes people go through harsh times before things get better. It's not something we like, but it's true of life. Something that's a bit of a trend I feel in DRGIII's writing.