Hi everyone and happy new year to all of you. I had the chance to use the new 300mm during the christmas holidays and I'm summarising my thoughts here. Feel free to ask me any questions. What impressed me the most is sharpness and the optical stabilisation. The former is excellent from f/4 already (I used this aperture a lot) while the IS is excellent also on Panasonic cameras. I managed to get sharp shots down to 1/6s and 1/10s with the GX8. With the E-M1 and the Sync IS mode, I reached 0.4s (only once but still impressive). Granted those are extreme tests but it shows how good the optical IS really is. Bear in mind that shutter shock can be severe at critical shutter speeds. The autofocus motor is very fast and silent on both Olympus and Panasonic cameras. The build quality is amazing, it feels like the best Pro lens Olympus ever build. It is also the largest and heavier M4/3 lens. On small cameras like the E-M10 or E-M10 II it can be uncomfortable to use. On the E-M1 and GX8 it's ok. I used the lens hand held for 90 minutes at a soccer game and only felt a little bit tired at the end. So yes it is a big lens for a m4/3 camera but you still get some of the advantages you expect from a smaller system. If I have to mention a negative aspect, it would concerns the bokeh. In some situations like a bird on a tree, the out of focus branches in the foreground and background have hard edges and doubles images so the bokeh becomes nervous and unpleasant. In other situations with subject at a longer distance it is fine. It is a large, heavy lens and the price is quite high. But if we consider that the lens gives the same angle of view as a 600mm on a full frame DSLR, there is some advantage there (but I know that some people might have different opinions about this kind of comparison . Below are a few images and a video shot in 4K with the lens on the GX8. You can check more images in my full review on MirrorLessons.