The beginning where he talks to Cortana, it totally reminded me of the movie Her. [1] It seemed fascinatingly real. Although that bit might have been pre-recorded, I think we will eventually get there, where a computer's voice and its interaction would seem indistinguishable from a human's.

[1] http://channel9.msdn.com/?wt.mc_id=build_hp [~1:12:50]