Released in 1970, the Mat-124G is the last twin lens reflex camera Yashica ever produced. While the Mat-124G lacks some advanced features, it's a well-made camera and is rather small by medium format standards. It's a solid choice if you desire to try out a twin lens setup, but don't want the extra weight of a Mamiya C330, or are afraid to break the bank with a Rolleiflex.
Let's get the negative out of the way. For me, the Mat-124G possesses two major caveats. Firstly, the camera cannot focus close (only up to a meter) without a clumsy, now-hard-to-find adapter, which makes portraiture and other genres of photography challenging. Secondly, multiple exposures are impossible to perform, which is a huge bummer for me. If you don't care about either of these limitations, then the Mat-124G could be the perfect twin lens camera.
Ergonomics are excellent, and make for quick, simple operation. All exposure information is easily viewable during waist-level operation. Aperture settings (f/3.5 ~ f/32) and shutter speed settings (1 ~ 1/500) are viewable through a window on top of the lens. These exposure settings are adjusted via twin dials to the left and right of the lenses. The match-needle light meter (ISO 25 ~ 400) is also conveniently located on top of the camera in front of the lens hood, though the meter takes outdated 1.3V mercury batteries. Focusing is achieved by rotating a knob with your left hand, while the shutter release is tripped with you right index finder. The matte focusing screen is not the brightest, but it's good enough in decent light, and I've seen much worse. As standard for most waist level finders, there is a pop-out magnifier for critical focus. Other features include an automatic crank advance, and a self-timer for when you want to get in the shot, or don't have a cable release handy for tripod work.
Did I mention the Mat-124G is small? Below is a size comparison with my Mamiya C330. It's really not any heavier or larger than a typical 35mm SLR.
Below are some photographs I made with the Mat-124G and Kodak TMax 400 film. I'm really impressed at the sharpness of the lens, even when shot wide-open at f/3.5.