My company recently rolled this out. I am not a fan, as this feature was previously located on bottom left, which I am not only conditioned to navigate to but it feels more intuitive, as the taskbar navigation for other apps are defaulted at the bottom of the screen and it is easier and more natural to move the mouse and your eyes toward the bottom than to the top. It takes me extra time to navigate between mail, calendar and tasks, albeit seconds, but it messes with thought processes and flow. While MS want to make this navigation consistent between products, it would be optimal to offer users the ability to move the icons similar to the taskbar or icons on a desktop to where users can easily access them. I desperately want to move them back to the bottom, but they are locked in top left position and there isn't even the option of moving the mail icon down after, say, the calendar or tasks icons. As with other comments, MS should seriously consider making this customizable for users.