I don't read much sci-fi/fantasy, because I tend to find the extensive exposition somewhat tedious, and the ideas vaguely juvenile. A totally unfair generalization, I'm sure, but there you have it. The Glass Tower, however, was highly recommended by two friends whose opinions I trust, and it isn't that long (sorry, Game of Thrones fans), so I gave it a whirl. And enjoyed it.
I will say up front that the book does suffer from the flaws of the typical sci-fi works. The writing is perfunctory, and you have to be willing to overlook things like characters named Thor and grandiose titles and classifications and explanations. But it also has the strengths of the best examples of its kind: interesting ideas, and the sense of exploring a possible future and considering its probability. The characters aren't as fleshed out as one might like, but there's enough there to care about them.
One of the more major themes of the book is an underlying question of how political change happens, and the role of religion versus political action. Its perspective on the issue is, perhaps, a bit drastic, but the way it plays out is interesting. There is also a question of what it means to be human, which follows somewhat predictable paths of thought, but I appreciated the importance granted to sexuality.
All in all, an interesting book. Not a must-read, but certainly a pleasant way to pass an hour or two. And as my friends pointed out, it really does cry out to be made into a movie.