Hanging
Two annoying problems here too (2013 rMBP w/ 8GB RAM):
1. Lots of hanging issues with Finder: scrolling, importing pics, moving files, SLOW loading of quick view (even small word files).
2. Beachball issues: this isn't so much an issue as a quirk. In Chrome my cursor randomly flashes to the beachball and back again - frequently.
I've been using Apple since my family got fed up with Dell in 1999, don't think I'll go back...but this has been disappointing/surprising. Not having any crashing issues, but the "glitchy" feel makes me feel like it wasn't quite ready.
On another note - any word on when Google is going to fix Chrome for Mavericks?