I kind of like how the new size looks. It's a little more elegant, and helps me take the book a bit more seriously than I would the normal mass-market paperback size. It also lets the designers have a bit more freedom with the cover. That said, there's no way the new size is going to fit in a pocket, a big minus for me.

Here's a look at the job a book designer does:
http://indiamos.wordpress.com/2006/06/30/making-castoff/