I regret that I've not had time to read this yet and it's had such good reviews that I know I'm missing out... I'll get to it one day!
On the Orion website for God's Spy, there's a trailer which is one of the more informative (and least cheesy) one's that I've seen.
You can also download a twelve page extract here.
A certain giant online website has the trade paperback priced at a bargain £5.99. The mass market paperback is due out in April.