I've used it for a few days, and I like it! Though, the toggle seems reasonable for future consideration.
For me, the covering of column headings when typing in the formula bar; and the inability to change the size of the formula font, are my biggest pains with the bar. But the ability to pin bar to the side would be my #1 update choice because when pinned to the side, the column headings are not covered, and the user does not need to expand the bar to see their block of text, so it's 2 for 1 as an update, as well as alleviating end user complaints regarding how to type more letters because they have a lot to say.
I would very much enjoy having this font applied to the "About Excel Version" to uniformly compare builds between users. I also wish for the ability to zoom in with mouse on the build page to clearly see it. The use case for this is remote desktop assistance where the entire screen of the user appears smaller for the IT helper. In my experience, chat applications are often used for the end user share a screenshot of the build.