do like the addition of the little tiles which is a nice and make sense. Not a fan of the buttons on the left, I liked the placement of them on the right side, also the fact that they weren't always their, maybe the shutdown, restart stuff could appear when you call out the charms like the clock. Also the notifications could also be done through the charms either with an additional button or as part of the over lay.
Then nothing should happen. Only the shutdown menu might open. The device is definitely not shut down immediately. But you're right, that positioning isn’t the best. How DevilishDB has already noted, you could alleviate the problem by holding the button for 2 to 3 seconds before the shutdown menu appears.