After a few months owning this lens, it's my favorite to keep on my body. I find it sharp even wide open and I love the colors and detail I get out of it. I also find its size and weight to be just right. I haven't had to shoot in situations where this lens has noted weaknesses so to me its a great lens to bring everywhere for outdoors, travel, and even family portraits.

For the money, size and weight, this is now my sharpest M.Zuiko lens -- and I also own a 45mm f/1.2 PRO lens. While not as flexible as the PRO zoom lenses, this little prime now stays on my E-M1 III whenever I'm not specifically on a job. Incredible crispness in the focus zones from wide-open to f/8 and a little beyond, and beautiful bokeh in the backgrounds. Lovely low-light pickup for a very low noise threshhold, even compared to the f/1.2 lenses. The 20mm frame is just slightly wide-angle of 1:1 perspective, so it's ideal for street work, and while not a true macro, the lens gets nicely close to things for detail shots.
A lot of pre-release reviews and comments complained about the lack of manual-focus clutch and function button on this lens, as had been included on most of the other PRO lens designs, but when seen as a low-weight, low-maintenance travel/street lens, those features aren't missed. The 8mm fisheye PRO also lacks those features and it serves its intended purposes extremely well. This is just a truly packable lens, whether on the camera body or in a side pocket, with no compromise on image quality.
The lens hood is a bit thin-feeling and basic, but that also follows the design idea, I guess, with no moving parts to fail and minimal weight.
The only other accessory included is a lens cloth which doubles as a wrapping pouch -- all branded with the new OM System logo. Again, basic but high-end.

Perfect fit to the EM 5, great all purpose prime.

The OM System 20mm f/1.4 Pro is often criticized in online fora for the large amount of purple fringing present if the sun is in the frame at f/1.4. And, in fact, this amount of purple fringing is very hard to get rid of in post processing and this is the Achilles heal of this lens. The fix is very easy; stop down to f/4 if the sun is in the frame. That's it. Problem solved. At f/4, the purple fringing is totally gone. Period. End of discussion.

I would suppose that the designers of this lens had to make a choice in order to get the lens to be this compact. The choice was to allow the extensive chromatic aberration with the lens wide open in extreem contrast situations.

So, I accept this Achilles heal as a minor flaw in the 20mm f/1.4 lens (with it's easy fix) and absolutely rejoice in every other attribute of this lens, and there are many.

The OMS 20mm 1.4 lens appeared to be ideal for my indoor event photography before its release. Initial reviews were modest in praise and definitely critical about uncorrected optical flaws. Well, I jumped anyway. A few days ago I used the lens in earnest, and I can say that it is really ideal for my purposes. The focus is fast, silent, and accurate. Wide open sharpness is all I could ask for, especially in the center of the frame. As for corners, at f/1.4, they really don't matter much. When the lens was stopped down a bit, there was nothing to fault for all practical purposes. The rendering is very natural, with sharpness and color saturation being very nice but not overdone. The bokeh is soft and pleasing. A few pictures were slightly low on contrast but setting white and back points in post fixed that easily. Despite the lukewarm reviews, I find the lens to be a very pleasant addition to my kit. If you go by real-world results, this should be a worthy purchase.

I bought the 12-100mm to have a relatively fast, high-quality super zoom for photographing trains and trolleys. I also have the excellent 14-150mm for times when size and weight are more of a consideration. I've used the 12-100mm on the Olympus E-M1 III, OM-1 and Lumix G9.

I seldom shoot wide-open but like being able to shoot at f4 in lower light situations. I don't shoot close-ups or selective focus, so the majority of my exposures are taken in the f/5.6 to f/8 range. I only shoot RAW files and all photos are edited in the current version of Photoshop before being posted or printed. The primary end-use of my photos is posting on Flickr or occasionally making 8.5x11 prints.

I don't have any primes to compare with the 12-100mm, but the lens has a beautiful optical quality that justifies its size and price. The lens handles very nicely on larger M43 cameras but might be a bit awkward to handle on smaller and lighter cameras.