I'm always interested in learning about espionage, and recently learned a little about Pham Xuan An, and agree with your assessment about the gushing about him by the Western press. If a spy had done this in WWII working for the Nazis or the Japanese against the Allies, nobody would be gushing about him making him out to be some great awesome reporter. From what I learned Pham Xuan An wasn't allowed to leave Communist Vietnam after the war.
From the link below it indicates that he gave intelligence that helped decide several important battles. I haven't read the book so I can't expand on what battles, but I'd be interested in learning more.
From the link below.
"From Publishers Weekly
Bass (The Eudaemonic Pie) expands his New Yorker profile of Vietnamese journalist-spy Pham Xuan An into this atmospheric study of tangled war-time loyalties. Working from 1965 to 1976 in Time magazine's Saigon bureau, An became known as a well-informed and connected reporter. Meanwhile, he passed clandestine reports and top-secret South Vietnamese and American military documents to the Communists; his intelligence purportedly helped decide several important battles."