Do you like Nabokov - did you meet the challenge of Pale Fire?
Do you like Borges - did you enter his labyrinths?
If the answer is yes, then you will like Wolfe, and hopefully you will spend some time on Urth!
It is difficult to summarise these books. On the surface they are a bildungsroman detailing young Severian's amazing adventures on a far future earth. So far in the future that - to paraphrase an expression of the late, great Arthur C. Clarke - technology is indistinguishable from magic. But delve deeper and you will find multitudes of puzzles, mysteries and profundities. It is a book that demands rereading: I have read the entirety of it maybe 7 times and I've discovered something new every time.
There are drawbacks to depth, however. Sometimes Wolfe's prose can be tiring, sometimes one may wonder where the plot is going, or be frustrated when interesting characters are not developed and fall by the wayside. Wolfe challenges us to read actively, to think, to pick up clues. The sheer length is daunting too, but if people can put up with thousands of pages of Terry Goodkind or Robert Jordan, then maybe they can try this as well.
I feel that if Wolfe had chosen to write "real" fiction instead of Fantasy or Science Fiction, he would be lauded as one of the best American novelists around.