Recently I've noticed how many books there are that are written about books.
To start, we've got our book list books (The Western Canon by Harold Bloom, Book Lust by Nancy Pearl, 1001 Books You Must Read Before You Die by Peter Boxall), our books about organizing books (The Library at Night by Alberto Manguel, Decorating with Books by Marie Proeller Hueston [PS - here's a great article about organizing books]) our books about reading books (How to Read Novels like a Professor by Thomas C. Foster, Reading Like A Writer by Francine Prose), Our books about literary theory (On Literature by Umberto Eco, S/Z by Roland Barthes), etc etc.
Generally I try to stay away from books about books. After I finish reading a book, sometimes I look up criticism or reviews of it to get a wider perspective, but for the most part, I try avoid letting others tell me what to think about the books I read.
I remember in my intro to Comparative Literature class I took once upon a time, we discussed the importance of reading actual literature, as opposed to just reading about literature. The importance of getting to know each tree, if you will, rather than an overview of the entire forest.
So ... what books have you read that are about books? What do you think about them? Which ones did you like? Which ones did you hate?