For things like launching games that are already in the disc drive, it actually might be quite clumsier to use the voice and if the new features were about that simple fact, they wouldn't amount to anything.If you already have the game on the launch page as the last thing you were doing, it's a button press, a few directional movements, and another button press. Compared to possibly having to say, "Xbox... Go Forza Motorsport 5" twice, the button is a more robust solution.
We'll see when the box is out whether gamers prefer to talk to their console or use old-school buttons. I could just be a dinosaur, unwilling to get with the times.
However, if you are in a chat with a friend or listening to music in the background from time to time while you go somewhere, using Twitch and so on and so forth, then it can be useful.
For searches though voice commands run circles around using the gamepad for input. There is no comparison, it is a one horse race. That's from my experience with Kinect 1, I have it powered on all the time.