If you have read Vidal's essays carefully, you will see many of the same stories recounted here, at least the literary ones. Unfortunately, at least for me, they simply don't have the same comic and bitter vivacity of his earlier work, as they are toned down and moderated somewhat. I felt that either his energy or his drinking - which he alludes to and which was new to me - has dulled his sensibilities.
What is new are some of his stories and a more systematic treatment of the man you get so many fleeting glimpses of in his brilliant essays. Perhaps there isn't quite enough to him to make this all that worthwhile. Afterall, he has not had a great emotional life: he loved a boy when he was 18, who was killed in WWII, and he never really loved again. Instead, what he seeks is simple sex with no real involvement, and I don't think he understands what he is missing. That certainly explains the absence of love in so many of his novels, or its continual betrayal in the search for power and glory.
Nonetheless, Vidal has had a charmed career, and he built it by himself - "I worked" as he says, in contrast to his step sisters whom he says were 19C women looking for men to support them. There is less of his famed meanness and combativeness in this memoire and more of a man looking back with pride and some forgiveness. His essays are more fun, but perhaps less mature.