I picked up these books hoping to gain some insight into the actions of the Marine Corps in the Pacific during World War II. What I found instead was a sort of soap opera that rambles on for hundreds of pages without getting around to much actual fighting. For example, The Marines don't even get to Guadalcanal (their first major offensive) until the end of book III, some 1200 pages into the story. Those 1200 intervening pages are mostly conversations (ad nauseam) between stateside Marine Corps officers as they sit around headquarters, or go out on the town chasing skirts.
The small portion of the books that is devoted to actual battles is done in such a cursory fashion that you're left with the impression that the author either finds this aspect of the Marines' mission distasteful, or doesn't understand it well enough to write about it. Mr. Griffin could have deleted about 80% of his material, and would have ended up with better books, albeit still not good ones.
If you're the sort of person who likes to watch daytime soap operas, then you may enjoy these books. If, on the other hand, you're interested in military history, the banality of these books will leave you screaming in frustration.