[Bayonet] Came from a Leica Q2 and thought that was good. This lens takes it to the next level, never seen images like this from a lens/camera. Can't ever go back to a Canon or Sony now.

[Bayonet] I am a long-time Leica shooter and have been using several 35mm Summilux and Summicron M lenses. I listened to Mr. Peter Karbe's presentation on SL lens design, and appreciate the idea of increasing contrast to give viewers a stronger perception of the three-dimensionality of the image. I love to shoot wide-open to use maximum light designed for the lens.

When shooting wide-open, Summicron-SL renders images similar to Summilux but retains the depth of field of F/2.0 which fits better to my needs. This lens is indeed the best of any lens designed to date by any technical standards. The image details are alive by the rich scales of micro-contrast and micro-tones. Of course, this is a super sharp lens, but the sharpness alone will not bring life to the images. We are talking about Leica magic here!

I will not hesitate to choose this one over Summilux 35mm ASPH FLE or Summicron 35mm V4 Bokeh King for the image rendition. This Apo-Summicron-SL 35mm is truly a lovely lens technically and artistically.

[Bayonet] Leica M shooter for... years as well as Nikon owner. I switched to the Leica SL system with the Panasonic S1R and its 47 Mpix (did the same with Nikon Z7 and the Z 35mm lens) therefore I do have some ways to compare the two offerings. The Leica SL Apo-Summicron is always over performing the Nikon Z 35mm lens. Sharper - way sharper -everywhere on the field. Better color rendition too. No distortions visible (probably thanks to digital corrections). With the S1R/SL 35mm combo, the results are really above the M10P/Summilux 35mm, you got AF in the mix and twice the pixels count! Is this lens the new reference 35mm lens, I really think so... I have never seen this type of details and definition in any other systems before. Super expensive, very difficult to get (long waiting list), but the willing photographers will be rewarded with impressive results.

[Bayonet] Picture quality is what you have always expected from this brand of product.

[Bayonet] Due to the virus situation I have not used this lens nearly as much as I would normally have with a new lens.
However, I have been shooting in and around our condo and our outside terrace. In short the image quality of this lens is Simply The Best.
Regardless of aperture setting, from f2 on up to f9 (I usually stop at f9 with an occasional f11) images are sharp across the image, crips, lovely color saturation, contrast, all are excellent. And in a first, remarkably I have not been able to detect ANY chromatic aberration; no green, cyan or purple fringing. A TRUE APO lens.
A slight negative would be this lens, while smaller than I expected (this lens is like a mini or 3/4 size S lens) is still a little heavy and when mounted on my SL (601) the combo weighs just about 4 pounds.
However this weight is worth the slight bother to me to have have a general purpose lens that I can shoot all day in all settings and obtain images that are as good as I've been getting.
I live in downtown Scottsdale AZ and this shot is from my terrace of a sunset looking southeast.

[Bayonet] Very impressive results with either Leica SL2 or SL2-S. Better optics than my Canon 35mm mirrorless lens, but no image stabilization. No matter, the Leicas have in-body stabilization. Auto focus is fast and reliable, manual focus is very smooth, like the bokeh. All of these shots are handheld, and the camera hardly ever misses the mark.

[Bayonet] Other reviewers have nailed the unprecedented image quality of this lens, and I agree with them. I use it on the SL2 and have never seen the ability to crop very heavily and get highly detailed images.

What I wanted to comment on is the feel of the lens on the SL2. Like a good marriage, it adds the built from a solid block to the lens. Other excellent lenses from Sigma and Panasonic are in my lens collection and I am very happy with the image quality from them at much lower cost than the Leica SL lenses, but they feel pretty much like other DSLR/Mirrorless lenses, very nice, but NOT built from a solid block nice!

A final note is that the autofocus is instantaneous and silent. As fast and quiet as any lens I have used.