For those of you that are having problems with the voice commands. Re-calibrate your Kinect. I guarantee you set it up wrong. The instructions it gives you are VERY misleading. When it tells you to be quiet during the test make sure all noises that are usually going on in your household are happening. For example your washer and dryer constantly being used. Dishwasher in the kitchen. Make sure noises like that are on.
I currently have 2 TVs right next to each other because my wife likes to watch netflix or the news while I play. During the test I had her TV on throughout the entire thing. Now I have practically no problems even WITH her TV on right next to mine (within 3 feet of each other)
Here are some videos to show how well a properly calibrated Kinect works and how to calibrate it. Hope this helps!