I've been shooting since the late 1970's... but I bought Bryan Peterson's book to see what all the fuss was about. I didn't want to recommend a book just because everyone else says it's good... I wanted to see it for myself. It is actually a very good book. I was able to appreciate that he was careful to explain concepts in terms that everyone would probably be able to understand.
I haven't looked at Kelby's books.
Another great book is Michael Freeman's "The Photographer's Eye - Composition and Design for Better Digital Photos". Although, as the title states... it's really about composition and design. So it's a more geared toward intermediate levels and assumes you've already understand the basics of exposure.