Heh. I'd wondered in the 5th volume, but we were turned around so many times, I'd dropped it. Nice mind-screw.
Like this whole saga, the book rating will be very subjective. I had a lot of fun, and enjoyed the twist and turns and ridiculous fits of mightiness; rolled my eyes at some of the drama (though I got itchy eyes at some points) and in-depth search inside the characters brain-process (get on with it! Ohhh, that's why!), and loved how it fucks with your suspicions and it's own worlds-building. The shifty morality of most the cast (a point that would stick to most readers craw) bothers me none at all
Lots fertile ground for off-shot stories, but mostly neatly tied.
I so have to re-read all nine books now I know.