I've got my first POD book ready to go. I think it looks just great. In fact, I KNOW it looks better than the original edition published by Berkley Publishing Group years ago.I'm happy with Lightning Source. They have been very efficient. What I am not happy about is that they don't offer media mail as a mailing option so it costs almost $4.00 to print the book POD for ONE copy, $3.80 for postage and $1.50 handling to get the book out the door. That's almost $10 before you see a profit if you are an independent publisher selling online and not in bookstores. Of course, at 50 copies to a carton, the price/book drops, but unless you do special sales and/or ship via Ingram to bookstores, etc., it's one book at a time.
As Lynne sort of points out, there are two components to POD. If you are an existing publisher its a cheap way to keep product in print. But it doesn't improve the product..... If you are a new publisher / self-publisher, you are still stuck in the quicksand of no media attention = no sales, and I suspect an investment in mailings to individual bookstores is unlikely to pay off. They must get a lot of PODs, and its probably too time consuming for them to separate the wheat from the chaff. Sadly, they must count on established big-time publishers to do so. If a writer is not working with those folks, self-gratification at completing a project should be anticipated as the biggest payoff.