I bought this as my only lens when I bought the GFX 50S. I use the camera / lens for Landscapes and Architectural photography, and for those uses the combination is sublime. The lens is bright, sharp as a tack, and along with the GFX produces gorgeous images. It feels solidly made, obviously of high quality. The autofocus is fine and works smoothly. If you need a wide angle lens for your GFX, you cannot go wrong with this beauty.
I cut my teeth on the 32-64 but seeing that I mostly shoot landscapes, I eventually needed to go wider. Enter the 23/4. It's a superbly sharp wide angle lens that outperforms many other wide angles in terms of sharpness and resolution. My favorite thing about it is it doesn't bury the far subjects the way wide angle lenses tend to do. So in photos like the Boston skyline that I've included, the buildings don't appear too small in comparison to the foreground. Image quality is the best I've seen in all my years shooting. Just bags and bags of resolution on this lens. It is a bit heavy for its size and buying 82mm filters for it isn't cheap but that's a relatively cheap trade-off for the quality photos I get out of it.
Fujinon lenses have always been considered excellent and this new generation lives up to expectations with great detail rendering, color and bokeh. The only knock I have is the focusing is slow, but this is a medium format camera not a DSLR. Focus speed is not as bad as I'd expected after reading reviews and compares well to other MF systems.
Quality lens. Built well, sharp IQ.