Let's get one thing straight. The story rates about 4 stars. But it left such a bitter taste in my mouth that I'm not sure I'll ever want to recommend it to anyone, much less re-read.
It's a form of madness that Gabriel suffers and it affects everyone around him. The reason why I can only give this 1 star is because I identified with Uriel too much. I felt despair and rage at having my choices and freedom taken away from me and forced to accept someone else's decisions, especially when they made no sense or collided so strongly against my own beliefs.
I wouldn't have been able to forgive Gabriel, and I resented Uriel for doing so in his final moments. I kept picturing myself in Uriel's place, right before he took the cyanide... and wanting to hurt Gabriel one last time by refusing to give him that which he craved the most. Nor would I have relented in letting him keep Uriel's ring.
(show spoiler)
The book pushed some of my boundaries and made me realise some new ones I didn't know I had. It's not for the faint of heart. You have to read it for yourself, though I don't know which is better: to have read it and visualise the world or not read it and miss out on such a disturbed depiction.