Received mine yesterday, only had time to update firmware (2.2 out of the box, 2.3 is available from Olympus) and play with settings and stuff. I forgot how cumbersome the setup menu can be on Olympus cameras mostly because it'd been so long since I set up my E-PL2. I find this to have been an invaluable resource to help in that setup: https://robinwong.blogspot.com/2015/07/the-robin-wongs-om-d-camera-cheat-sheet.html
Also, if you're in the US, I recommend getting a new cable or adapter for the battery charger. It supports 110-240V, but comes with a different plug and an adapter from Massdrop. But it's a standard IEC C7 connector, so you can just buy the cable... or what I did a long time ago for my old camera is get one of these Apple 'duckhead' connectors to plug the charger directly into the wall. It's been so long that I can't be sure if this is the same one, but I have one very similar to this that fit the E-M5 II charger perfectly: https://smile.amazon.com/Generic-Apple-Power-Adapter-Iphone/dp/B00OPVFV4A/
Finally, if you're in the US you also won't want to forget to go through all of the video modes and manually switch each individual one from 50fps or 25fps to 60fps or 24fps.
Also, if you're in the US, I recommend getting a new cable or adapter for the battery charger. It supports 110-240V, but comes with a different plug and an adapter from Massdrop. But it's a standard IEC C7 connector, so you can just buy the cable... or what I did a long time ago for my old camera is get one of these Apple 'duckhead' connectors to plug the charger directly into the wall. It's been so long that I can't be sure if this is the same one, but I have one very similar to this that fit the E-M5 II charger perfectly: https://smile.amazon.com/Generic-Apple-Power-Adapter-Iphone/dp/B00OPVFV4A/
Finally, if you're in the US you also won't want to forget to go through all of the video modes and manually switch each individual one from 50fps or 25fps to 60fps or 24fps.