"Ringworld Engineers" by Larry Niven

This is the second book about the Ringworld, following 10 years after the first one.  The franchise has grown to four books apparently.  I read some reviews online about the first two books, and many reviewers like the second one over the first one, saying that nothing really happens in the first one except the description of the Ringworld.  Well, let me give you a news flash, THAT is all the first book was about, and was GREAT in doing that, explaining a new and original concept, a sliver of a Dyson sphere.  The rest of the narrative (except the three main characters, Louis Wu, a puppeteer and a K'zinth) is pretty much secondary and falls flat.  Well in the second book, the entire book falls flat, since there is nothing really new that could be discovered that could overshadow the Ringwold itself.  Yes, yes, we learn that Pak protectors built it and about many other facilities on the Ringworld, but that was to be guessed.  Nothing in the second volume would strike the reader as powerfully as the description of the Ringworld in the first volume.

Indeed, we meet a lot of new humanoid species, apparently all developed from Pak breeders that were originally there, but so what?  All these hominid species which seem like forced earth-animal paradigms on the hominid frame are actually making the book seem silly.  Their habits and ways are very predictable and silly.  They don't seem real, but seem like cartoonish characters from a children's book.  And they have sex all the time!! With everyone!! Come'on! I know our own society is largely very backward about sex and physical intimacy, but every hominid fucking every other (3m Grass Giants with 1.2m Hanging People???) is just ridiculous and silly.

Finally the story is tired.  A puppeteer (the Hindmost in this case, though Nessus was cuter) kidnaps Wu and Chmee (the new name for Speaker-to-Animals) and takes them to the Ringworld in order to find a large-scale transmutator machine which never really existed except in the wrong speculations in Louis Wu's head.  They find the Ringworld off-center and heading for a collision with it's sun, and run around trying to find out how they can save it, after Wu had sex with the locals (again) and this time Chmee also had sex with no less than six K'zinthi females, which could even talk! Silly.

Anyway, Niven never intended to write another Ringworld book, but because of the storm of fan mail he got, much of which from scientists and science students (MIT students chanted "The Ringworld is not stable" at the 1971 ComiCon in San Diego), exposing, in length, all the things why the Ringworld cannot exist, he decided to write a sequel and explain all the inconsistencies.  That's how we got the RamJets on the ring's perimeter, the sewage for the oceans, the sun-powered mega laser, etc. etc.  It was an attempt to close the holes in the first book, without introducing too many new ones.  However, there are still two more volumes, so one has to guess that there are more loose ends.  However, this reader is not curious any more.