This is where the rating system gets weird. I'm giving this book three stars for purely subjective reasons. Anne McCaffrey is a great writer and Pern is a fully realized fantasy world filled with interesting and well-developed characters. And the fantasy elements are in full display in the form of humans and dragon-like creatures working together against a common foe. But most fantasy stories fall into one of two categories, those where the fantastical elements take a backseat to theme and plot, and those where the fantastical elements ARE the story. Being a fairly simple person, I prefer the latter. I like my antagonists to be undying zombie lich-kings and other-dimensional horrors so hideously alien merely thinking about them will make your brain melt. Alas, the Pern series is character-centric and the bad-guys, corrosive extra-terrestrial "threads" that fall from the sky, are incidental. So if you like your fantasy/sci-fi with an emphasis on traditional literary themes unique to no particular genre, the Pern series is right up your alley. If you want laser-battles with evil robots or wizards and chicks in metal bikinis fighting hell-knights mounted atop flaming skeleton steeds, you might want to look elsewhere.