The world drives this story. Discovering the facets of the world inside Incarceron and its relation to the Outside is what pushes the plot forward.
The characters are interesting, but not fully fleshed out.
There were some plot twists, but some were also expected.
I think overall, the story just didn't push the scifi of the story enough. It tried to set the Outside world in a timeless era, where Time has stopped. It tried to set Incarceron as living prison that gorges upon itself. But it doesn't go far enough. It is still too common, still too natural. I believe a lot of it stems from the diction that the author chooses. If she had chosen more obscure words, more words that were twisted from time and age, then I would not feel like this world is just a caricature of our world rather than a new one completely.
Three and a half stars rounded down because it is an engaging, interesting book that I have not seen the likes before in all my scifi readings. Rounded down because it just doesn't have the wow factor to push it to a four star. It was good, just not amazing. Recommended for people who like new worlds.