Everything between the first and the last chapter in this book is, in a word, excellent. Amazing combination of the first contact theme and hard SF (I am a hard SF fan myself, so I like those parts best). However, the first chapteer is too long and I found it so boring that I almost gave up reading the book. If you have the book, hang in there during the first chapter, it is worth it. As for the last chapter, it is too disappointing, even for Lem. If you like happy endings, don't read this book. It seems to be the thing with all Lem's works - they're all great, but they are all missing something. Maybe he should have teamed up with some other author. But anyway, this is the book I would reccomend.