An incredible book but one that does not stand on its own.
Carson's light-touch erudition is completely at play but this does not prevent some of Red Doc>'s chief pleasures coming from a reader's knowledge of Autobiography of Red. Even given that, the later volume is simply not as peerlessly successful as AoR (what could be?).
My reservations/joys with Red Doc> were more than ably captured by Parul Sehgal in her Bookforum review.