After using the beta at work, if only for a couple of hours, after a short time the changes didn't really affect me.
Only a handful of things stuck out as problematic to me:
We're using 2007 iMac's and while I know that's the 'bottom end' in terms of the install specs, the font did seem quite light unlike the previews available online, and in finder it had a habit of fading into the background.
After reading others thoughts on this and not having Retina at home either, it is a slight concern. Otherwise I think the font choice is brilliant, actually. Looks very clean in the previews, hopefully mirrored as much as possible on my samsung monitor on final release.
The folders are too bright for my taste.
Ditto the dock, though dark mode and an app to change folders will be helpful here.
I'm not overly keen on Safari's re-design, there are obviously other choices so I'll look but after being a default browser for me since Snow Leopard, it's a bit disappointing. It feels sparse yet overly confusing at the same time.
Perhaps I got tired of the mind numbing work and I'm looking for something to blame on that one.
Otherwise pretty good, feels like always, buttons do what I expect them to do and I really enjoyed the transparent windows!
Might wait a while to upgrade, simply because I love Mavericks, I think it's the best OS ever put together.