According to the description, the following can be done "In the living room":
•Navigate your Xbox One console using your device’s keyboard and touch
•Control your media and set top box with the SmartGlass remote control
•Browse the web on your TV using your mobile device
•Enhance what you are watching or playing with SmartGlass companions
•Increase performance with faster connections and reliability
Also, when out-and-about, users can "Search, browse, and pin content to play on your Xbox One console" as well as "Track achievements, get game help, message friends, and watch game clips."
The app is available now and the Xbox One launches Friday November 22nd in most countries.