Military thrillers aren't among my preferred genres, so take this review with a grain of salt. If you're a fan of David Poyer and his Dan Lenson series, you'll probably like this book better than I did.
I found many of the details too esoteric for someone like me, and I don't fancy joining the US Navy just to find out what some of those acronyms mean. Similarly, especially near the end of the book, Poyer has way too much fun describing how to operate Juliet submarine. The amount of jargon might intimidate some readers.
That being said, as thrillers go, The Weapon had great pace. A couple of early setbacks, then a tense, action-packed climax and quick resolution. Not much I can complain about there.
The characters weren't great. I didn't like Dan Lenson much; Poyer didn't seem to spend much time establishing him as a useful person. Then again, since he's the main character of a lengthy series of novels, this just may be a sign that Dan Lenson was once a great character who is now suffering from Series Decay. I'm not qualified to judge that.
An OK book, but it's not what I want to read. It has very little to offer beyond mild entertainment; I usually prefer books with a little more depth.