Ten years after writing the popular "Ringworld", Larry Niven has bowed to public pressure, and written this sequel. Good job too!
Those who read the first book will certainly recall Louis Wu, the 200 year old human who visited the Ringworld with his trio of partners. Now, twenty years later, he is forced to return in much the same conditions. This time, however, the Ringworld is in danger of destruction. Somehow, the million mile wide ring has become unstable, and is headed for collision with it's sun. Upon finding this out, he changes his mission to one of salvation for the thirty trillion beings inhabiting the structure.
He searches for the centre of control for Ringworld, finding out many things along the way.
This book is much like it's predecessor; it doesn't seem that much actually happens, but it's interesting all the same; discoveries take up most of the text. Uncovering and explaining various mechanisms required by such an esoteric structure is the main attraction offered.
I think the only criticism I can offer is that, like in the last book, reactions by some people are sometimes... odd. Insults or events that would seem to lead to conflict are ignored. Insults or threats are passed over. I only noticed a few of these discrepancies however, and they could be mostly be explained away by a changed culture.
That's all the negativity I have to write; can't call this a book review page if I don't say something bad, can I?
BTW, A small but important note: The ending leaves room wide open for a sequel, that which I'm about to read and review this very minute. Look for it soon.