I have been using this MW about 4 months--since 3/22/2013. I have not had any real problems with it. In fact, overall it does a very nice job.
However, I found the keypad buttons lacking in really useful choices. The Popcorn, "Sensor", "Turbo", "Keep Warm", "Function", and "More/Less" buttons are really entirely useless. Even after reading the manual thoroughly and their intended purpose, they don't really do anything worth their presence.
I would FAR rather see something more simple yet FAR more useful. In place of the "Quick Min" button, include 3 simple buttons: "10+", "30+", and "60+". Those would simply add 10, 30, or 60 seconds to the current cook time. Those buttons should work that way not just before cooking but also during cooking.
Finally, the Start button should not need to be pressed most of the time. When a cook time is entered by any means, wait 2 seconds in case it needs to be canceled, and then immediately been cooking.