I hope they will fix some bugs as well. The top one on my personal list would be fixing broken exfat support https://superuser.com/questions/321161/disable-automatic-fsc...

Or maybe Bluetooth automatically switching to "reduced audio quality" (I know, I know, it's a feature, not a bug...)

Or wait, the kernel panic I get every once in a while would be nice: panic(cpu 1 caller 0xfffffe00318c8a1c): DCP PANIC - ASSERT!AppleDCPDPTXPowerController.cpp:538 No device added after powering on the rails. HPD=0 - dcpav(27)

I haven't had a system that felt so unreliable since Windows 98. :D