Image courtesy: Mobile01.
Mobile01 posted the full Olympus 40-150mm PRO lens review. You can find plenty of image samples you can download to review for yourself. Here are the reviewers conclusions:
1) Image quality is very high straight from maximum aperture (bets sharpness at f/4.0). 40mm shaprness test image here. 150mm sharpness test image here.
2) Bokeh is very natural and soft
3) purple fringing is only present at 40mm in extreme conditions. At 150mm there is no purple fringing
4) Anti flare performance is good althaugh not exceptional
5) There is almost zero distortion
6) Very fast autofocusing
There is no doubt this is a very high quality lens from Olympus!
P.S.: More image samples can be seen on Flickr (by Terakopian). And here is a curious image of the Silver E-m1 with teleconverter attached: