No matter how strong the plot, if the prose style is deficient then you're looking at a bad book. Likewise, a fairly flimsy plot can be brought to life by an entertaining style of writing. This is exactly what happens here.
Andy McNab will probably be the first person to admit that he's not inviting comparisons with Charles Dickens or Thomas Hardy as an author. However what he does, he does extremely well: - espionage thrillers with lots of "insider" details concerning spy-craft, well written action sequences (something that Tom Clancy could learn a thing or two about), a central character who is all the more believable due to his flaws (once again Mr Clancy, please take note). No, it's unlikely to ever be considered "great literature" but Conan Doyle's Sherlock Holmes stories were seen in the same way when first published. They are now regarded as the foremost examples of the detective genre. McNab's books will, I believe, receive similar "serious" recognition once the literati critics get used to the idea of ex-soldiers writing novels.
If you're looking for a book that will change your life & make you see the world differently, the you'll be disappointed with this. However, if you're in the market for a tightly written thriller with enough suspense to make you want to keep turning the pages right until the end (where you'll find a twist that may raise a smile), then this will fit the bill better than most.
Buy this book, open a can of beer, put your feet up & take the phone off the hook. You will not want to be disturbed!