Right now the Assassins Creed Revelations Beta is only on the Playstation 3 and is only accessible to Playstaion Plus users or people that have connected their PlayStation 3 with a Uplay-enabled game. The beta will run from now until September 11th. In the Beta, as you enter the Animus assuming a persona, then developing abilities and customizing your appearance. You have targets all around you that must be taken out as well. Three maps and four modes as well as much, much more are available in the Beta. Check out a full ACR Beta Guide and more info on it here.