As a book reviewer myself I spend most of my time reviewing fairly recent but not that recent books. mOST of them are books I find at the library and have been released within the past several months at the earliest. That said, a lot of my books are the kind that fall under the radar mainly because I have a fascination with obscure authors, particularly in the YA genre.
Most of my books are fiction and the few non-fiction I do are, charitably, fairly old. The most chronologically recent book I reviewed was Stephen King's Holly and even that I reviewed six months after it came out. Every so often I'll hit one that's fairly recent - I reviewed Apples Never Fall within a month of its release - but the majority of the books I've reviewed over the last three years, they're the kind of books that I guarantee you that people should be reading but are so low-profile that I can't imagine a major publication wanting to review them even by accident. Those are, naturally, the kind of books I'm always drawn too.