I was playing around with this image and remembered that I used a Pentax 120 mm Macro lens on a 6x4.5 cm negative. I like the lighting and tonality of the image but I'm not at all happy with the way that lens, used too close in, accentuates Rene's nose and draws out her chin and mouth. While it's entirely personal taste, every time I get too close (closer than 6 feet?) with a lens I find myself disturbed by the way faces are rendered. This image would have worked better for me if I'd used a longer focal length or stepped back a few feet and then cropped in during post processing.
This is, I think, totally independent of format. I am equally uncomfortable using a 50mm lens on an APS-C camera if I step across that imaginary line at six feet. Too much foreshortening. Given the focal length equivalents on cell phones we tend to see a lot of foreshortened social media images and eventually (sadly) the general population will come to regard that look as normal and appropriate.
Again, everyone's taste is different but for my satisfaction the longer the focal length (up to a point) the more flattering the image for normal faces. My all time favorite film combination was the Zeiss 180mm f4.0 on a 6x6cm Hasselblad. Currently, when shooting portraits with a full frame Sony camera and their wildly good 70-200mm f2.8 G lens I find myself constantly ending up at about 120mm on the zoom ring. And when I shoot in m4:3rds I like a 50mm, really like the 60mm and love the 70mm focal length. Images done with that optic are generally done from further away from my subjects and the final result is a bit of flattening which de-emphasizes the nose and, with good posing, can also make chins look more normal. The longer focal lengths also allow me more control over depth of field and finally, with the best of the older lenses, even in smaller formats the bokeh (or the quality of the blur produced) can be very calm and lovely.
Why would I show a photo I find fault with? So we can talk about the possibilities.
It's good to get close. There's a line you probably shouldn't cross. Yikes, foreshortening.