So far, this does exactly what I expected and wanted it to do. It moved the "sheet" tabs from the bottom to the top of the screen.

Sure, it makes the top info bar fatter, but I'm okay with that instead of having to look down all the time to switch sheet tabs, which I do very often.

2-MONTH UPDATE: after 2 months, I'm still loving this extension. It's so simple of a change, but it's enough that it just "clicks" with my brain more to look for "tabs" at the top of the screen. In fact, when I am on a computer that DOESN'T have this extension, I find myself quickly adding it (like I am literally right now on my spare laptop). Thanks again for making this great little extension! :D