Why is this better than just using the USB port on your Mac to charge your device? Well, the reason is twofold:
First: That takes up an extra USB port. If you are using a MacBook Air, that might mean the device has to vie for space with other components.
Second: It can take a lot more time to charge an iPad via your MacBook or MacBook Pro than through a wall connection. In fact, if your USB port isn't powered, charging the iPad can take a ton of time.
Third: For business travelers, this eliminates the need to pack the external phone or iPad charger alongside the laptop charger.
At $34.95, this is a slick and relatively cheap device. It also doubles as a standard iPad charger -- and considering Apple sells those for $29.99 (granted, the Apple model also includes a 6' extension cord), we think this is a good deal.