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.
Sadly i’ve just discovered that from Going Postal and onwards there are no annotations. Seems the project never finished with all the books :/