In short, if you're considering reading Niven for the first time, pick this book first. It's not a very long book at all (I read it as a teenager) so if find you hate him, then you don't endure much. :) You get the interesting/strange world premise, lots of interesting inter-human development, plot twists, and a small/manageable but not overwhelming dose from the science aspect of sci-fi.
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One of the first sci-fi books I read. I'm not really a sci-fi fan, but I picked this off my Dad's bookshelf because I liked the cover, and it was short, unlike most of his other scifi books. However, this had a good balance - enough to be interesting, not enough to lose my attention completely. Most of it was spread throughout the book, so I wasn't getting a huge dose, which helped. The first chapter has a little more, since it has to set up the premise, but it's not bad and if you get through it, it's worth it.
I love how posing the idea of a strangely-shaped world (such as Ringworld) can ripple down to affect how people think, evolve, and task manage. Sure, some call it rehash - pick a new shape, write a new book - but we see it in our world, after all. Think about how Islander communities differ from inland river-side communities, and those from mountain communities. In Niven's "world", Humans inhabit massive trees that radiate outword from the central star like spokes on a wheel, with "tufts" at each end that are the only habitable portions of this world. Yet we discover that there are indeed people surviving in rogue floating tufts of greenery without trees attached, which is unthinkable to tree-dwellers. (Think: pirates) I believe our cripple main-character gang eventually joins up with them for a while.
One of the most facinating parts to this book was how these isolated little tuft communities develop, both comparing them to the advanced group they initially came from (great plot twist there, btw), and to other tuft communities both more and less regressed. There's quite a bit of tribla warlike action going on in one of the trees, between the two end tufts. The tufts with access to information - teaching tapes, teachers, etc - are obviously more "civilized" than the ones without, such as the dying tuft which sends out our gang of cripples. But it's neat also to see that the "civilized" tufts are still devolving into sort of a caste or maybe master/apprentice system? Not sure how to characterize it. Character interactions are fascinating on the small scale, between our main group, and on a larger scale, between the other tufts they come across.
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(I'm annoyed at the cover on the new editions. They damped down the bright green color of the old book - which was a small part of the premise, that in the trees and floating greenery even the air was almost tinged with green. Small, but I still remember it.)