Bug fixes! Major ones. So the crashing issue with C4K has been fixed, as have other quirks and stability issues that v3 brought.
We still don’t have an exposure meter in video anymore if you shoot in manual mode. Hopefully that means another firmware version will be coming soon too. It seems this may have been a quick update to get the camera operational again. Regardless, i would definitely update to this if you installed V3. I would update immediately! If you haven’t updated to v3, then it is at your own discretion whether you want the better autofocus upgrades and other benefits v3 brought.
I am glad Olympus brought this firmware fix out so fast. I am in California on a shoot and I use the E-M1.2 on a gimbal for B-roll. Came just in time since I shoot in C4k.
As usual, check out the resources page for more info on firmware.