Haven't read it yet, but have heard great things about it so far.
Vanity Fair has an article written by Mark Bowden, the same guy who wrote Black Hawk Down and Guests of the Ayatollah, on General Petraeus.
Here is one gem that was passed along to me:
In academia you publish and subject your work to criticism and comment, and sometimes your ideas are shot down. It can be a humbling experience. In the military, you publish, and then you arm yourself for battle. If your ideas are wrong, you don’t just suffer criticism. People die
It is long, but I figured, I'd pass it along.
http://www.vanityfair.com/politics/features/2010/05/petraeus-201005?printable=true