Best answer: While both the SmartGlass software and USB keyboards do what the Xbox Chatpad can, only the Chatpad allows you to type quickly and comfortably without setting the controller down. It's a fantastic accessory for any player. So, yes, if you need a better way to type on Xbox, you should buy the Chatpad.
Microsoft Store: Microsoft Xbox Chatpad ($35)
Full story from the WindowsCentral blog...