This book is a clever polemic on bolshevism - or Stalin's version of it as enforced by very bad men like Lavrentii Beria and Nikolay Yezhov. It describes and discusses nasty zealots in grey uniforms enforcing draconian laws and weeding out the 'undesirables'. I think that's a take on the Nazis, or at least the German army's uniforms (WWII) anyway.
Hats off to these men who had it published against all sorts of idealogical barriers in 1963. Possibly courting a close inspection of the Soviet gulag.
The book itself is a trope of an advanced world peeking at (in this case) a medieval one and the observers are prohibited from interfering. Frank Herbert used it, Adrian Tchaivosky has used it, Peter F. Hamilton has a bit of it it in one trilogy, Iain Banks also used it. I liked the idea but the execution was not brilliant in that the 'adventures' of our hero Anton meandered more than followed a clever plot.
It is a book of its time. The verbiage is often clever, with some great one-liners thrown in, but the style is dated and heavy in places. I certainly understand why it's rated a 'classic' by many people but its pedigree did not make it a great book for me. 3.5 stars.
The start was slow, but once we get comfortable and familiar with the premise of the story, the authors reveal a great commentary on our own world....especially what we are seeing in politics these days.
A very short, though at times dense, read. The grim parallels to our own world are loosely veiled. Overall, a very enjoyable read.