We´ve had the chance to test the Olympus OM-D E1 at this event. By enlarge a good camera but to be honest coming from Nikon full frame, nothing for me to consider. Low pixels, to much buttons, too small for me, personally.
I really was wondering about the decreasing quality using higher ISO values. Not having to much time to test that step by step but in total pics became more worse than with my other cameras – Sony RX100m3 included (which even has more pixels and a smaller sensor).
Sorry for that Olympus.
But I´m sure there is a great potential around for it.