I’m not in on the secrets but he had a coauthor this time, Grant Blackwood, who has coauthored with others. I would guess Blackwood did a lot of the writing. It works well, with just the right snappy tone to the dialogue and a lot of authentic-sounding detail.
The reviews of the book on Amazon were very mixed. It seemed like people either loved it and gave 5 stars or hated it and gave it 1.
FYI, I read Vince Flynn’s American Assassin in 3 days. I thought it was great.