Please fire the person in Microsoft that thought the charms thing is ok
I have a quick test that the person that thought of, designed or approved the charms should take.
Test: make them sit down in a computer, open terminal server and get into a Windows Server 2012 machine. Now ask them to try to show the charms bar instantly with the mouse 10 out of 10 times. It is not possible or you would have to be a ninja to do it consistently. If they fail, fire them! (Did Ballmer take the test?)
Most people are not ninjas therefore it is not a nice user experience. Start button was way better. People need immediate reaction for an action, not guessing which one is the exact pixel to stand on top of. Make it simple, have a reaction for an action. Make a little triangle in the corner to fire it up. (You can also fix the screen with the apps but that is a separate topic)