The preface of Black Marxism is more a mini-biography of the author than what I usually expect of a preface. Still very interesting read and introduced several of Johnson's ideas and concepts.
I did find myself wondering at one point what Johnson (would have) thought of Tyranny of the Structureless. (Tyranny of the Structureless was around over a decade before Johnson published Black Marxism, but I have no idea if he actually knew of it. Very much hoping it comes up later in the actual text.)