This feature seemed like somewhat of a gimmick until I actually got one of those cards along with many other swag items at Computex earlier this month. I popped it into my digital camera as I was running out of space on my other card, and quickly my camera's USB cable started falling into disuse. The card also came in handy when I had to get pictures of the previous night's exploits from an acquaintance—simply popping the card out of my camera and into his PC did the trick.
The only question mark with this product is the number of insertions the USB plug can take. However, since it's basically the same price as other SD cards, you have little to lose.