http://www.eurogamer.net/articles/digitalfoundry-hands-on-with-xbox-one
In terms of performance, it's pretty rough game to behold. There's tearing all across the screen, even during menus. Mowing multiple enemies down with a vehicle results in circa 15FPS performance as well - so let's assume the target is 30FPS here. Also, reflections on windows and the checkered floors around cafes update at half the usual frame-rate, which makes the presentation look incredibly choppy. At the Microsoft E3 presser, the game was actually running with v-synced engaged, and it's safe to say that performance was dire - we'd hope that this is comprehensively addressed in time for launch.