I got this about 24 hours ago and it's been raining, so it was hardly a good environment to try.
I've considered a lens with a maximum aperture f/0.95 but the Leica Noctilux series were anywhere from US$6000 - $10,000. Voigtländer produces 4 lenses with this maximum aperture and with a micro Four-Thirds mount, not electronically connected. These are generally less than US$1000. All of these lenses are manually operated.
While I have used lenses manually more recently, they've always been electronically connected to the body. Being totally without a backup system will be like being in my teens again with my original Fujica SLR and two Pentax-screw-mount lenses.
This Mitakon 25mm f/0.95 looks a bit as it's trying to emulate Leica. It's rather heavy, being metal and all. For US$400, but with a $50 discount, I felt it was okay for a good experiment. It seems perfectly sized for the Panasonic GM5 but it is somewhat heavier than the camera body.
It seems quite sturdy and seems better on the Panasonic GX8. The box was somewhat unusual.
If you're interested in a test of the lens, you should look at this one.
It has a click-less aperture ring, something quiet for video but a bit annoying for still photography. It definitely reminds me of a number of lenses from the 1970s with the Depth of Field scale and all.
I mounted the lens to the GX8 and took it out around 3:30 p.m. I kept the aperture around f/8.0, to remind me of earlier days. Besides, it was a bit bright for f/0.95. I popped the EVF into the vertical position to remind me to keep an eye on the aperture ring.
Lens flare is an issue. The coatings obviously weren't meant to deal with a lot of sunlight, but who would have thought that someone would use it that way? I found the lens to be good but a bit odd. You'll see from the photos that it takes care of direct sunlight in a most unusual way.
Next, I need a warmer evening, so I can take some photos outside at maximum aperture. That may be a few days from now, as Northern California is getting rain and a cold front.
Update 2017.02.25: I took a little trip to the Golden Gate Bridge overnight and got some photos. We've had a deluge of rain and flooding but it's been relatively dry the past couple of days, giving me a chance to use the lens outdoors.
I've noticed a small problem--it doesn't seem to focus to infinity and this isn't surprising. After I got the lens, I was warned by someone else who had the problem.
Update 2017.03.07: I thought I would add a couple of night time photos from last night. I needed better stabilization or a tripod to steady this, even at f/0.95. The Panasonic GX8's IBIS isn't very good, probably similar to the Olympus E-5 from 2010.