I have a hard time visualizing some of the settings described in these dystopian novels. I don't know if it's because there are too many futuristic events going on that I don't get because I haven't experienced them, like "projections" or "transports", or if it's because of my terrible reading comprehension. Either way, I got a little lost in a few places trying to visualize exactly what the characters were doing, and there were one or two slow spots, but overall I give this book 4 out of 5 stars. Whenever I had to put it down to do something else, my mind was thinking about the next time I'd be able to pick it up and read a few more chapters. To me, that's a sign that I'm really into a book.
One last gripe about Possession is that the ending is completely unresolved. I looked up the author to see if she is making a sequel, and it sounds like she is writing a companion novel. You can read about it here if you are interested. I found a small description of this companion novel online, and in the description, it sounds like the author will indirectly answer questions about Possession characters through new characters.
Anyway, if you pick up Possession, let me know what you think!