As I said to WhatIFoundThere, I think her comment has helped me clarify things - the writing isn't hand-holdy about the sci-fi aspect, but it does take great pains to make the Eastern European setting feel well-researched and comfortable. Which slips into the background (where it should have started) when the sci-fi stuff comes to the foreground. Which also makes better sense of my whole 'do I read too much foreign fiction for this to feel smooth?' reaction,