The first 200-250 pages are fairly interesting and intriguing, although a lot of the "surprises" are pretty easy to guess. But the last 100+ pages, it goes downhill fast. The main character makes one inexplicable decision after another. And then... it just drags and on and on. With another 75-100 pages to go, it's pretty clear what's going on, and yet we suffer through the protagonist coming to the same realization in the most slow, agonizing, boring way. Overall, an interesting premise, but the execution fell apart in the final act.