Got it, started reading it in bed yesterday. It reads really well. I'm somewhere in the background of Hell right now. I've been familiar with Praemal/Ptolus for years now, like many other fans of Monte's work. There were hints as to the complete background of the world, and surely I already know chunks of it, but it's great to see it all pieced together in one place.
That said, do I like the background? Damn right I do! It's a blast to read, and every page I find some bits that I could use as encounters, adventures or complete campaigns. I can't wait to run a campaign using Praemal.
What I like particularly: the whole Cosmology so far, the "late European"/slightly German feel of the Empire of Tarsis with the Prustans and so on, the political climate which reminds me vaguely of the Roman Civil War, the influence of HP Lovecraft's work, the minerals and metals that reminded me strongly of the alloys and minerals of MERP/RM (which is a good thing).