I read it years ago. It's very good.
It put LeGuin on the map, if I remember right (but I probably didn't).
Don't trust the communist utopia too much, Franc - every society would work great if every member was totally sold on the prevailing ethical system...and stayed sold.
The "back and forth through time" structure of the story is awesome - but I don't recall time actually being different in that story, and the FTL doesn't hardly matter; its about two societies on each planet of a binary pair - as if our moon was inhabitable. One is a market economy, one a propertyless commie fantasy. The backstory is that all the communists got fed up and left the nice watery planet to go live on the deserty one and prove their utopian ideas.
The major plausibility comes from the ability of citizens to move between them, avoiding the issue of promulgation and indoctrination, it doesn't come from her deeply considered economic structures. But that's hardly a criticism, because the question in the heart of the reader about the two options isn't supposed to be settled by it.
If the person making a decision is not the one assuming the risks of a potential mistake, then the decision is more often a poor one. -T.Sowell
I hate tmaq so much that I completely misread his post.