This is a pretty interesting look at heavyweight champs from the 60s to 80s. If you followed boxing, nothing here is earth-shattering, or new. The possible exception is the difference between how boxers rated Ali (lower) compared to how the general public does.
George Foreman is charismatic, the rest kind of egotistical (part of being a champ), and because of that mostly predictable. Each, besides Foreman and Norton, do a lot of self-endorsement.
If you like boxing, and followed these guys, it's worth watching just because anything they say is kind of interesting. Without that context, it's probably gong to be boring, and the characters not very interesting.