Each chapter has an illustration of the person (or people) discussed, so you get a bit of a biographical feel for them. The main part of the book is certainly the text, but the writing is very approachable for young readers, written in a way that is really conversational- just like if a friend was telling you about this person and what they did.
The book is really short overall, so it's easy to read in a sitting or to be broken up into multiple sittings. While it does contain facts, it's not quite a reference book. It is really just a fun book for kids who love to learn (and parents too- I definitely learned some new things in the book!). Would recommend for kids who want new facts/knowledge given to them in a funny and approachable way.