Gene Wolfe is several orders of complexity higher than the Foundation series. Its threads are tied together in ways that will blow your mind. You need to be totally, totally awake to understand what you are reading. You don't get 'clues'. You get one chance to grasp something Wolfe is telling you. It is extremely rewarding as well as intellectual.
I cannot count the number of times I had a "holy fuck" moment, Wolfe is unbelievably smart.
You know how people on Reddit and 4chan look for 'mindfuck' movies.
This book, The Book of the New Sun, is on another level. My mind changed its frame of reference about a dozen times reading it. Normally a good author manages to accomplish that once.
There is basically no way I can ruin this book for you by hyping your expectations. It is just that good.
Also; I must beg a favour so I can return one to you. You must read the book (there's two volumes of 4 books total) while listening to a piece of 'music'. The Voyager Recordings.
This is not actually music. It is what the sensors picked up on the spacecraft as they pointed their arrays at the different planets.
If you listen to this while you read the book, it'll make it much more immersive.
I know this sounds dumb as hell, but it is hard to explain. Just do it, you'll thank me later.
P.S. Your initials won't happen to be N.D would they? Foundation is his favorite book also. If so I won't hold it against you, I'm not that kind of guy, but do read and listen. It is rewarding, and important, I think. I know I somehow changed after doing this, it was as if the world had deeper textures and certain things just clicked or something. Maybe I'm a strange person on the internet, but it is worth taking a risk to find out.