It’s the first change to the Office default font in more than 15 years.
It used to be called Bierstadt, for those who know that name and similar alternatives like Grandview, and the other contenders for next new font. I don’t remember exactly how it looked, but I hope it’s one of the ones where a capital I and a lowercase L look different from each other.
I used to like sans serif until I realized that serif fonts make text more readable and lead to less confusion. For instance, the L / I example earlier, and 0 (Zero) and O (Oh).