So I looked it up on Wikipedia:
Set in a Roman Catholic monastery in the desert of the Southwestern United States after a devastating nuclear war, the story spans thousands of years as civilization rebuilds itself. The monks of the Albertian Order of Leibowitz take up the mission of preserving the surviving remnants of man's scientific knowledge until the day the outside world is again ready for it.
This description, combined with the fact that it won a Hugo award, the generally positive spin of the article, and the fact that my friend liked it, made me want to read it. My thoughts were "Why have I never heard about this? I thought I knew all of the science fiction classics."
I finished reading the book a few days ago. My reaction is mixed. Although there are clear moments of genius, the overall work seemed uneven. The author spends a lot of time on things that do not make much sense, and there are a lot of loose ends and things left unexplained.
For example, there are Latin passages sprinkled throughout the book that are never translated. I cannot read Latin, and I am not familiar with church liturgy, so I had no idea what these things meant or how they might be important.
I was also never clear on how much mysticism the author intended there to be. Especially in the first book, there are strong hints that one of the characters is extremely long-lived and that prophesies are being fulfilled. But it is never explained if this is real, or just mistakes and coincidence.
Maybe this was the intention of the author. Maybe he intended to show the complexity and confusion of the world. But if so, the execution of this attempt was indistinguishable from sloppy writing.
However, the parts that were good were very good. Several of the characters, scenes, and situations were very memorable and thought-provoking. It was almost as if the author had come up with ideas for insightful creative allegorical scenes and characters, and then threw the rest of the book together in an attempt to provide background for these star scenes.
The book reminds me of one of those movies where there are a couple of really good actors and a couple of really good scenes, but the rest of the movie is just a muddle that only serves to set up the good scenes and give the good actors the chance to show off.
So, by the standard of 'memorable thing to think about' the book was very good. By the standard of 'well-written story' it was not. If you like philosophy or history or social sciences, and don't mind the occasional chaotic ramble, then I recommend this book.