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.
I recently finished the Discworld series by Terry Pratchett. Wonderful books. I read it in order of subseries which is a good way to get into the books, but it does make it a bitt jarring when going back to the first books, before Pterry really found his stride. Once I get around to a reread I think I'll do it chronologically.
As a change of pace i continued with Fear and Loathing in Las Vegas. Something of a whiplash change from Discworld and a it got me a bit too amped when reading right before bed. Still a very fun and interesting read.
Now onto SAS: Rogue Heroes, which i started earlier but have yet to finish.
Sadly i've just discovered that from Going Postal and onwards there are no annotations. Seems the project never finished with all the books :/