There were a lot of ideas in this book: multiple alien races, genetic luck, boosterspice to extend human life, and not to mention a giant Ringworld with a collapsed civilization...but everything is scratched on the surface. The majority of the story is Louis, Nessus, Teela, and Speaker traveling across Ringworld to discover how they can repair their damaged ship. The ending isn't quite satisfying with so many unanswered questions.
The theme of genetic luck is interesting, but it seemed a bit far-fetched to me. It would seem that luck is a trait that is substituting for something else. One of the characters refer to it as psychic luck at some point. Makes me think that it's not so much escaping the odds as it is the ability to somehow control them unconsciously. I wish it were explored more!
There are really strong gender roles in this novel, especially by the closing with the introduction of two new ones. I would have preferred Teela to be more independent. If she was so lucky, why does she need a man to rely on?