I am really liking it. If you liked the 360 you will love the One as it does everything the 360 did only better. There has been a drastic improvements in the arena of voice controls. So much so that they are actually convenient to use. The controller is a thing of beauty. I thought the 360 controller was pretty much perfect, but the slightly revised shape, surface treatment to the sticks and the feedback on the triggers have made it even better. About my only complaint is the DVR controls for the cable/satellite box, but I hear that is due to Comcast and DirecTV not playing nice and could easily be fixed with a software update.
As far as video game quality goes it is an improvement, but not as drastic as going from the PS2 to 3 or Xbox to 360. Give developers a year and I'll be it will be close to it.