I haven't read any of the Rogue Warrior books in the last 5 - 7 years or so (I know that there are several new ones out since then), I used to love the books.
While it would be a FAR stretch to call myself a friend of Dick Marcinko, I have met and spoken with him on several occasions. I have even given him a bottle of Bombay Sapphire. Interesting guy. Perhaps a bit bloated in his books about his own abilities, he is much more down-to-earth in person (the books are sensationalized fiction after all).
I especially enjoy his Leadership Secrets of the Rogue Warrior book. While still active duty and since then I've tried to live that code - particularly leading from the front.