First the good points:
- an exciting story involving high intrigue and the world's most wanted terrorist
- confrontation between the USA and England on one side and Iraq and Iran on the other side - how topical can you get?
- a techno-thriller about an undetectable submarine and lots of other modern military hardware
With all that going for it, H.M.S. Unseen should have been a great read. But what did we get? A book that makes the exciting moments (stealing the submarine, the shooting down of the Concorde, etc.) sound dull, and makes the in-between parts positively sleep-inducing.
On top of that, the ending is really poor. (Spoiler alert - don't read any more if you want to avoid learning how the book ends.)
The President of the United States decrees that the government of Iraq (i.e., Saddam Hussein) is to be punished. The President's national security advisor implements an attack which results in a major portion of Iraq becoming flooded. The national security advisor proudly reports to the President that Iraq's economy has been dealt a major blow from which it will take them 10 years to recover.
So it's apparently considered legitimate to cause major suffering to the entire population of a country just to "punish" the dictator at the top. In reality, Saddam is presumably totally unconcerned with his people's suffering and will probably find himself in a strengthened position, since he and his people now have proof that they have a common enemy with no moral scruples.
Of course, reality has now bypassed this portion of the book. So although the story is supposedly set in the near future, it must now be considered a total fiction which isn't even remotely possible.