I first read World of Ptavvs when I was about 16, and remembered nothing of it other than the title when I came across a copy last week. That surprised me a bit since I'd felt fairly strongly about most of Larry Niven's other works--loved Ringworld, hated Footfall. So I grabbed it up and since it's really just a novella, thought I'd finish it rather quickly. World of Ptavvs didn't hold my interest, though, and so I put it aside in favor of other more substantial books and took more than a week to complete it. If this were not the first of Niven's Known Space books, honestly there would be no particular reason to spend time with it. Other reviewers will cover the plot--suffice it to say that this is a real sci-fi gadget-driven-"technology and its consequences" story with cardboard characters--I couldn't even say, afterward, who I thought the main protagonist was. Characters have never been Niven's strong suit, ideas have, and in Ringworld that was no bad thing. But World of Ptavvs lacks the alien environment of Ringworld to a great extent, and so Niven's explorations are less compelling. There were moments of interest, and the idea of a superwar that destroys almost all sentient life in the universe is horrifying, but the method Niven postulates given his own premises is so obviously flawed that it took me a mere 20 seconds to think, "Wait, that doesn't make sense, couldn't they...?" One plot point, the exploration of space by dolphins (!) was completely dropped and seemed almost entirely irrelevant to the story. Completist fans of Known Space will surely want to read World of Ptavvs. Other sci-fi fans might prefer The Apocalypse Troll by David Weber, a work indebted to Niven but in some respects better written; or the Peter F. Hamilton Night's Dawn series.