This book is a 3.5. I decided to round up to 4 because it's Chuck Palahniuk and contains some gems of brilliance that really makes you think.
The Party Crashing story line is absolutely brilliant and approaches the level of Philip K. Dick. Specifically, the Nighttimer story line, the I-SEE-U Act, and the quarantine echoed Dick's The Penultimate Truth and elements of A Scanner Darkly.
What takes the book down is a transition of about 20 pp or so in the middle of the book. It is a little slow in coming together and is a little jarring as it is a sharp break from the first-half of the book. But once it comes together, the book gets back on track.