Icon Battery Pack For iPhone

How's this for an external battery pack for your iPhone 3G/3GS? The Icon Battery Pack for iPhone looks just like the iPhone's battery icon, and even shows its visible 'battery power', allowing you to know how much additional juice that it can provide your iPhone. This device is supposed to be able to juice your iPhone up for an additional 3-hours worth of talk time, or audio playback of 18-hours. Would you buy a battery pack that looked like this?