New Preview Function--Awesome or Ho Hum?

I recently became aware of a new feature. I can offer previews of my books right here on my blog! I've been experimenting with All Fall Down on the sidebar. You can preview the first few chapters by clicking on "preview." So far I think it's pretty awesome and readers will like it. It's nice that it's so versatile.

But here's my question: do you use the preview function before you buy a book? Or do you just buy a book from the back copy? For me, I've mostly just bought the book if the back copy was intriguing, but with the ease of the preview function now, I might change my ways.

So, tell me what you think of the new preview function.  Awesome or ho hum?

(And just to experiment a little more, here's the preview for The Captive)