Other than FW drives not spinning down during system sleep, no issues with 10.9.3 on my Mini, iMac or MacPro. I guess Apple has moved on from FW and probably won't fix the FW sleep glitch.
None here. When I leave my office wifi and bring my early 2013 MBPr home I had problems connecting on home wifi, even in ML. With 10.9.3 all seems fine with both MBP and Mac Mini.