Although one might take issue with the title and conclusion that JFK and LBJ were the last "two great presidents", there is little to criticize in the quality of the writing and use of sources.
One of the main themes of the book is the rehabilitation of LBJ's image. As Hodgson shows, sometimes to the point of distraction, Johnson was hardly a country bumpkin and he was not a traditional Southerner or part of the more conservative Texas political stock. He was from west Texas and shaped by more of a Midwestern or even Western mindset. He had the misfortune of following a more media friendly JFK, who was very conscious of using his charisma to disarm critics and cultivate the Camelot myth. Johnson was by far the more effective of the two in manipulating the legislative process to achieve his goals and pass a host of bills that would have an enduring legacy, although falling short in his vision to attain the goals of the War on Poverty and The Great Society.
To be fair, JFK was inching in the direction of more progress on Civil Rights and other areas that bear a more liberal stamp. However he was hamstrung by Southerners who controlled committees and legislation. It certainly can be argued, as Hodgson does, he might have achieved more on that front had he been re-elected, a likely prospect. An assassin's bullet in Dallas consigns such speculation to the realm of counter-factual history. His most striking triumphs would come in the realm of foreign policy, notably the Cuban Missile Crisis, where he went against the advice of his advisers and averted a potential nuclear catastrophe. Whatever his accomplishments or failures, JFK would help modernize the presidency with his media savvy and use of polls, and serve as an inspiration for millions with his vision.
Ultimately, both men would be bedeviled by Vietnam and it would be the albatross that would sink LBJ and stain his historical reputation until relatively recently. Hodgson devotes a significant portion of his account to the topic of " What would JFK have done?" He makes the case that Kennedy would have continued to be ensnared in the conflict, but again, that is a counter-factual proposition that can be argued but not resolved.
Regardless of one's stance on that or perceptions of the presidents, the closing chapter is powerful and beautifully written and well worth the effort of reading the book as Hodgson develops his arguments and provides a smashing conclusion.