Part One of this book (which is two thirds of it) is quite readable and is interesting because it gives a contemporary account of France during the German invasion of 1940. It doesn't make for a particularly entertaining novel, but there is some good writing as we follow the lives of various groups of people in Paris and in the countryside, both civilians and soldiers.
It's not always easy to keep up with who is who though, as some characters disappear for such long stretches that I'd forgotten who they were by the time their names cropped up again.
Part Two is written in a different style. We get 120 pages without any paragraph breaks, and I found this quite tedious and harder to read. It just rambles on and on, pretty much the same content as Part One, but even more dofficult to follow. I reckon paragraphs are there for a reason, and to do away with them for no good reason other than trying to be different seems absurd (to use a word that Sartre was fond of!).
I find Sartre's philosophy very interesting and this book is easy enough compared to some of his non-fiction, but as far as his novels go, I would recommend 'Nausea' more highly than this.