Expose has never worked/looked better!
I've noticed the same. Animations of Exposé/Mission Control and folders opening from Dock are very smooth now, unlike Sierra.
Is it because of Metal 2?
I actually liked the look in Panther/Tiger/Leopard better, where the whole selected window where highlighted in bright blue. Now it looks more like Snow Leopard with just a blue outline for selected window. Maybe I'm dreaming but think they made it Leopard style again in Yosemite/El Capitan/Sierra, but now it's back to Snow Leopard style.