I love it, especially since I'm in my car 2 hours a day. Like tk, I find that location based reminders aren't dependable, but that's a Google Now problem and not a Moto X problem. Time based reminders have worked for me every time. As for voice detection I find it works spot-on if in the idle state, but sometimes if it's already displaying the home screen it might not catch me. Overall it gets me about 90% of the time though. I also think I've gotten slightly worse performance after putting a TPU case on the phone even though the cutouts around all three mics are perfectly matched. May be nothing though.
After awaking to listen to me, it works best for me for web searches, questions like "who won the game last night" (I LOVE THIS and am getting addicted to it!), and "Start" commands for launching apps. Although it generally gets the right SMS name and starts composing correctly, it usually quits recording before I'm done dictating an SMS message. I find that tapping the voice recorder mic from they keyboard works remarkably better for this, but I'm not sure why unless they are using a different software on the back end. Plus, that still requires an additional few taps to get to, which defeats the point of touchless controls. However, the fact that both Touchless Controls and Google Now can be constantly upgraded via app updates makes me feel that these will only improve over my 2 years with the device.
If you are only getting 50% response, I'd agree that you need to definitely give re-training a try.