Perhaps it's because they are sharp, funny and engaging. Or because she rarely goes into an exposition about her vast knowledge, or disses an author for having written a clunker. She reviews the book she's read, not the tomes that came before or might come after.
And then I read this:
That's from her recent review of Justin Cronin's The Passage. How can I possibly resist?
Read the review. Don't know about the book, though.