I've been waiting for the Olympus for a while now. I think at the point i'm probably the first in the US at least to even throw one on a kopter and fly it so i thought i would give a bit of a review of what i think in the kopter side of things.
The stabilization is phenomenal! Above is a side-by-side of what is considered the "standard" for stabilized video in the multirotor world right now and that is the Panasonic GH2. The cool part about this camera though is the fact that the sensor is what's being stabilized and not the lens. This is pretty huge because it means you can use any lens you want and still see the advantages of the stabilization. If you try it out just make sure you have the stabilization on "mode 1"; it makes a huge difference. I found that although very close, the EM5 does do a better job at stabilizing the footage.
As for video quality i would have really liked to have seen 1080 at 60p but if you don't have a camera now it will be perfect. I purchased this camera as a possible upgrade to my GH2 but may stick with the GH2 for now. Although i will say that the video quality of the two is very comparable. I did like the way the video looked straight out of the EM5 a bit more then the GH2 though.
When it comes to functionality on the kopter it is great. Very small, relatively light, and easy to position. I do like how small the kit 14-42mm lens is on it because it keeps the camera from being to front heavy and makes balancing the camera on the gimbal almost pointless. I also like the fact that the EM5 has an analogue video out which means you can downlink your video straight out of the camera and see exactly what it's seeing, without the extra mess of an HDMI converter. One more small benefit is that the screen folds straight up so you can make any settings changes without lifting the kopter up to see the screen.
A last worthy not is the how customizable the camera is. Both dials on the top, and even a few of the buttons on the camera are all customizable so you can change exactly what they change. Which is very helpful when it's on the kopter. No fussing with menus when you don't need to which is great. And although there is a very thorough menu system on this camera, it is relatively intuitive to navigate.
All in all i would highly recomendd the camera. If you already have a camera like the GH2 i don't know if i would recommend you upgrade to this for the price ($1,100). But if you don't have a camera yet or are looking for a second camera i would highly recommend this one.
Side Note: I'll be interested to see what options i can come up with for taking still pictures witht his camera on the kopter. There is not physical shutter release port and i don't think there is an IR sensor so we'll see what happens.