The first three novels are very good as straight up literary fantasy and read well without trying to mine them for deeper meaning. The fourth one reveals a lot of things but I lost a lot of steam reading it and didn't feel the desire to try to piece it all together.
There's a lot of people who apparently just keep reading these books over and over again and try cross-referencing them against other works and looking up the etymology of the obscure words to try to solve the mystery. But honestly, that feels like a project of diminishing returns. I have one or two short things written by Gene Wolfe scholars that I might read if I really feel like it later but I am done with him for now.