So far I haven't noticed many setbacks with 10.10 (and I'm enjoying the new UI so far). Performance is good, every now and again software will refuse to install itself because it doesn't recognize my OS version. I can't remember the last time it crashed on me. Sublime is a little buggy, it'll go totally black for most of the screen, and I have to resize it to force a repaint, but that usually only happens when I have my desktop monitor plugged in (which is rare).

Overall, it's been a really enjoyable experience - a stark contrast to the horribly buggy mess that is iOS 8.

I am. It's less buggy than iOS 8 betas but it's somewhat rough if you're not used to living with beta software. Dock freezes twice a day, Safari's rendering is faster but app itself is quite slow.

Personally I have high tolerance for this, but I know some folks would get frustrated quickly.