Fantastic assesment of Halberstam's Vietnam reporting in Neil Sheehan's A Bright Shining Lie: John Paul Vann and America in Vietnam. Along with Fitzgerald's Fire in the Lake, Halbertstam's own The Best and the Brightest and Karnow's Vietnam*, one of the best American involvement in Vietnam books (imho).
Also, it's really wild to compare Halberstam's position in Vietnam and his relationship with John Paul Vann with current Iraqi/Afganistani reporting.
*In all fairness, I've never read Making of a Quagmire, though I've always meant to.