I never used it, but I'd love to try. I think that it's a great concept, because I rarely use Fx buttons, I can't memorize them. They're useful for debuggers, but every IDE defines them differently, so I just gave up. I think that I'd love this feature and it's sad to see it gone, I'm considering buying M1 Macbook 16" and according to rumors it'll have ordinary keyboard.

Of course Esc must be a separate physical key, but they did it right in the latest revisions.