For me this was completely unreadable. The prose style was terrible - dry as dust - and the content was inaccurate, boring, and offensive. The first 30 pages are full of nationalistic and racial stereotypes that seemed just silly to my mind. I know it was written in 1931 and a lot has changed in the intervening years, but I simply couldn't find a way to make this readable.
Stapledon may be one of the greats of early SF, but I found this just plain bad. I didn't finish it, and I'm happy to pass it on to others who might find something in it that I missed.