Fortunately I've managed to somehow miss out on the Metro calculator app. It looks to suffer from the problems described here, only worse yet than existing calculator apps, on account of the size of all the Metro widgets compared to the size of the 21+" (non-touchable!) monitor sported by your average desktop PC: http://prog21.dadgum.com/107.html
Really? I use Windows 8 daily and have never seen the full screen calculator. When I open the calculator, it opens in Desktop mode and presents the same calculator as what I used in Windows 7.
Edit: Hrmmm... Looking at the screen shot in the other comment, can't you just dock the calculator to the side like other metro apps?