I found the first 150-200 pages (30-40%) of this book to be boring at times with the story's strong suit mainly being its humour. But that absolutely changed when 2 certain characters meet and from that point on this has been an incredibly good book.
Beside this being an interesting science fiction book that thematizes a world-ending crisis, I feel that at its core it is just a really emotional and funny story about a very unlikely and beautiful friendship!