The author describes this book as pastoral, and I gotta say, that's dead on for me. It's got the kind of plot where, when explaining it to my girlfriend I had to keep repeating "no really I swear it's good"-- there's some intense, wonderful, delightfully out of the ordinary world building going on here, but it unfolds beautifully over the course of the plot, not crammed down the readers neck.
I'd heard some complaints that this book "doesn't really have a plot" and I disagree deeply. It's not a very actiony plot-- the book mostly consists of two people becoming friends and going through grad school-- but the growth and change that the characters go through is fascinating. I spent a lot of time yelling at my girlfriend about how they were going into the WRONG SPECIALIZATIONS DAMNIT and any book that can make me care that much about that is really something.
Overall, super enjoyed this book, read it in an afternoon, bought the next one the very next morning and finished THAT in about three hours flat. Second one is more "action", but loved both of them.