I've been using Tahoe on a 24" iMac, and still have Sequoia on my other Mac. I spend a lot of time in Finder and my goodness the UI is killing me in Tahoe. Safari too. Something about Sequoia just feels so clean and sharp and Tahoe all these floating UI elements, app icon redesigns having a bit of blurry look to them, ughhh. Pains me every time I use the iMac to do a bit of work.
As a (not very good) UX designer/instructor, Finder's new toolbar buttons are killing me. The way they pop-out is really distracting and (to me) breaks the visual hierarchy of a Finder window.
I'm definitely holding back my final opinion until the OS releases, but in terms of visual hierarchy, contrast, and legibility, Tahoe seems like a step back to me, so far.