Image courtesy: Mirrorlessons

Mirrorlessons posted the 300mm with EE-1 red dot sight review:

The most difficult thing when using a long telephoto lens is to quickly compose your frame after spotting your flying subject. The first few times I couldn’t track anything because as soon as I looked through the viewfinder, I couldn’t find my subject anymore. All my reference points were lost. One solution is to keep your camera very close to your eye with the lens aimed at the same thing you are looking at. If you see a bird flying, you start following it before moving your eye to the viewfinder. Practice and experience also help.
With the EE-1 you can take pictures while putting some distance between yourself and the camera and keeping an eye on what’s happening around your frame, something an EVF won’t allow you to do. This is also important because you can observe how the birds behave in the air, how they change direction and where they go. Once you know how to use it, it can either help you enhance your tracking abilities (meaning one day you won’t need the EE-1 anymore) or become an inseparable companion for your wildlife photography.

Marcin Dobas also reviewed the new lens and writes:

Once again I was pleased with image stabilization (it’s not easy to keep the camera steady when you are winded after constant running).I definitely appreciated the fact that a lens, with focal length equivalent of 600mm even with the converter 840mmm, can be quite comfortably held in your hands while cross-country running. That’s a big plus. It won’t come as a surprise to many readers that I don’t particularly enjoy running after deer with a full frame 600 f4. Whatever you’re into I guess. Yet again I appreciated small size of the equipment, especially compared to a SLR. However, comparing it to 400mm f / 4  APSC, while it is smaller and lighter the advantage would not be as pronounced as in the case of FF.

First sample images of a M.Zuiko 300mm F4 taken by Photographer Ángel Lazagabaster at NamenColor.
Wasabi Bob has posted some full size photos taken with the prototype Panasonic 100-400mm lens on Flickr.

Preorder links to the two new MFT lenses:
Panasonic-Leica 100-400mm lens at Amazon, Adorama, BHphoto and Panasonic. In EU at WexUK. ParkCameras.
Olympus 300mm f/4.0 PRO lens at Amazon, Adorama, BHphoto, GetOlympus. In EU at Amazon DE. WexUK. ParkCameras.