The books are very much worth rereading. The layers of jokes and references are so deep that you likely won't catch all on the first or second reads.

I can recommend The Annotated Pratchett File, https://www.lspace.org/books/apf/, for an in depth review of a lot of jokes and references. It explains a lot of things that are hard to catch if you haven't grown up in England. Many things i thought Pterry had made up for the Disc is just references to real world things and events.