Two things I’ve found about the firmware update.  First, it wipes all your camera settings and restores them to the factory defaults, shutter sound effects and all, so you have to go back and re-do all your setup.

The other thing is just that you don’t actually have to get out your USB cable, you can copy the firmware onto your card via a card reader, put it back in the camera and just do it that way instead. But the camera behaves weirdly afterwards with the card that has the firmware on it - took ages to start up (I gave up waiting) so it’s better to pull the card and delete that file on your card reader again once you’re done, I found.

Anyone found any useful features added by it?  It seems like it now remembers the size of focus point you like in the EVF better than it did, but perhaps I’m wrong about that.  It didn’t clear when the camera went to sleep, anyway.  (And I initially thought it was letting me use smaller focus points in the OVF now, but that was my mistake!)