I got Angry Birds Rio and Shazam for free. Really, the only reason I have it is for Rio and their Premium App of the Day for Free deal.
One thing I hate - the one click purchasing. Say you accidentally tap the Buy Now button next to an app while trying to scroll. BOOM! You've bought it, no chance to confirm and zero possibility of a refund. This already happened to me on an app I had no intention of purchasing. Thankfully, I had not yet confirmed my credit card info for the Appstore, so the order is pending. If it sits dormant for 5 days, they will cancel it. That's the only way I can avoid wasting the .99 on it. Serious flaw.