This is a departure for Harris, being set in contemporary Britain against the background of international politics and it works very well. The narrator's voice is very clear as he moves from amused detachment through bewilderment and fear to taking charge of his own destiny. The references to the current political scene are incisive and often witty. It's written with pace and verve. I read it on one sitting so I suppose I found it "unputdownable".
If I have a criticism, it's that the trail is a bit too easy for the ghost writer to follow.
I still prefer his earlier novels, especially Fatherland and Enigma, which were not set in the current time and I re-read those often. I can't imagine re-reading this one as there is not quite enough going on outside the hunt for the story hence only four stars.