Since the "New Xbox Experience" update in Fall of 2015 the Kinect has essentially become useless. The swipe navigation is no longer a thing for the Xbox user interface and the voice recognition is terrible. It takes me longer to tell it what to do that to just use the controller for navigation.
I can't speak for it's accuracy in games since I do not own any Kinect enabled games. But I can say that I had high hopes when I first got it for changing and streamlining my Xbox One experience but that has most certainly not been the case.
I do not recommend anybody purchase one of these. It's only redeeming factor is that you can use it as a microphone for online chat, but even then the Xbox comes with a headset so the point is moot.