[C-mount] The Pentax Monochrome, following Leica's lead into digital black and white photography, opens the doors for affordable, high quality rebirth of B&W images for hobbyists and professional photographers alike.
As a young hobbyist I will never forget watching my first image emerge in the development pan in the dimly red light room. A second AHA moment was my first view of B&W negatives taken with my first Leica rangefinder camera and lens. I now have a third, and possibly most important event, that occurred when I reviewed my first images using the Pentax monochrome camera -- finely nuanced B&W pictures that virtually jumped off from the view screen. My first thought was that I had been shortsighted and tight-fisted by my initial response to the high price of the Leica Monochrome cameras. My second thought was that there now exists a clear, challenging future for hobbyists and professional photographers. The question most photographers now have to answer for themselves is how best to capture their images. There is a bright future awaiting B&W photography. The Pentax monochrome is an incredible photographic instrument at an unbelievably low price. Leica opened the door to 35mm photography and now has opened the door to digital B&W photography. The Pentax DSLR is the first to follow Leica and has done so with its SOA improvements to DSLR cameras. It will not take long for all the usual copycats to compete in this new and exciting dimension of photography.

[42 Hz] This camera appealed to me because it promised a quirky experience--an optical viewfinder and no ability to capture color. Based on my usage of the camera to date, Pentax delivered on that original promise. The viewfinder is bright, and the sensor produces tonally rich images. This is my first and only digital camera from Pentax, yet I didn't have trouble learning the camera's core functions. It feels well-made, which adds to the joy of using this camera. I think it is a great tool for exploring black-and-white photography.

[USB 3.0] I posted the most-recent review of this camera, where I tried it and loved it, but fretted over its autofocus performance--so returned it.

That was a mistake. The black-and-white quality from this camera brought it back to me. There's just simply no way to easily replicate the results by editing color. I've spent lots of time trying to do this. In some scenarios, I get close, but at the expense of much effort.  If you shoot lots of black and white, you will not be disappointed with this camera.

And since I've had more time with the camera--and have used a wider variety of lenses with it--I've learned that the autofocus is better than my initial impression, snappy-fast on some lenses, in fact. If mirrorless AF is considered a 10, I'd give this an 8.

[C-mount] delivered fast, installed easily, updated driver, worked perfectly, my scanner now works.

[3.45 μm] I haven't picked up a color sensor camera since getting this camera. Behaves very much like film where you use color filters to correct color tones into B&W.

[C-mount] For all of us who cannot spend the money on the Lecia, Pentax gives us a wonderful Monochrome digital camera. Based on the K3 chassis it is a Monochrome only Pentax K-3 Mark iii. It is an APS-C professional-level camera. With excellent ergonomics that Pentax is known for. Yes everyone is dashing off on mirrorless but the bright, eyeglass-friendly viewfinder is wonderful. With a nice catalog of lenses, this is a black-and-white camera that can be used in any situation. Finally black and white with excellent fine resolution, usable high ISO, and professional grade. The images have fine detail, highlights, and shadows. Easy-to-use menus and settings that address every situation you may encounter. For those who remember all those color filters for black and white are usable to manipulate the the images before tripping the shutter button.
Two things to consider. LCD panel does not flip up or rotate. I use a Ref a right angle viewfinder by Pentax. It works well on all the 35mm Pentax cameras and some other brands. It rotates and has a 2x setting which is nice for macro. The other thing I have noticed is the very sensitive shutter button. It has a very sensitive and short motion to trip the shutter.
I can highly recommend this camera to anyone who wants to do Monochrome. You will not be disappointed
Monochrome is far from a niche place in photography. You see it in many venues. It is not limited now to the conversion of color digital or shooting film. We now have a well thought out Monochrome from Pentax at a more palatable price than Lecia.

[USB 3.0] To preface this story, this is my first DSLR and my first Pentax.
Before this I had owned two mirrorless cameras. 
First I started with a Lumix S1 but was looking to upgrade and convinced myself to sell everything to buy into the Fuji GFX system.
To my (and many others) surprise I was dissatisfied with not only the build quality of the 50sii but the images I was creating with it.
Something just didn't look right. I couldn't place my finger on it but things looked... sterile? 
I thought a digital medium format sensor was the answer to replicating my medium format film cameras but alas, this was not the case.
I wanted to capture a black and white film look with a digital camera but couldn't afford a Leica monochrome.
It was a risky move on my part but I sold my GFX after doing a lot of research into the K3iii monochrome.
The first day I took it out I knew I had made the right choice.
Images from this camera are pure magic and have tricked many people around me thinking it was film.
Match this sensor with a M42 adapter and throw some Super-Takumar, it looks identical to B&W film.
Love shooting this thing at night at ridiculously high ISO levels.
The build quality is like a tank. View finder is bright and easy to focus. Speaking of focusing, the auto focus is faster than some of the mirrorless cameras Ive used.
I don't ever want to go back to mirrorless after using this gem, there's nothing like framing your image through the lens.
My only complaint is it takes a second to get used to exposing correctly. You need to be very mindful of blown out highlights.
Images match that of any full frame camera I've ever used.
I love this thing so much I can only hope Pentax will release a full frame monochrome camera in the future to compete with Leica.
Anyway, if you love B&W photography then this is the camera for you.

[C-mount] I love where this camera takes me. Beautiful results straight from the camera carries me back to the 70's when I shot Tri-X almost exclusively.

[42 Hz] Amazing camera! Same classic Mark III feel, and just heavy enough to make you imagine you're a pro when you hold it, point and shoot. Yet, the image contrast, sharpness, and shades make this camera irreplaceable when compared to similar B&W shots taken by a color camera. Definitely recommend to a friend.
Thank you B&H Photo Video for having this baby in stock, and making my purchase experience a breeze, the shipment arrived in no time.

[42 Hz] Needed more USB 3.x ports with a controller, didn't need to be bleeding edge Gen 2.2.abyx.v10 (3.2 Gen 2 or above).
Did some light research, and really wanted to avoid Renesas from a previous experience. The card also needed to fit into a PCIe x1 slot, and other cards looked... dubious, with their USB C ports (3.0 x1 can't support over 8Gbps). Also don't have many C to C cables or devices that use it.
Don't need it to power devices beyond flash drives and just drive a powered USB hub with wireless receivers.
Installation was straight forward, and Windows picked it up immediately.