Sold the D750 and the 24-120 last month, so the Zf is now the only digital body in the house. Thought I'd write up how it's going for anyone on the fence, since it comes up here fairly often.
The dials are the reason I bought it and they haven't got old. ISO and shutter on top, exposure comp where my thumb expects it, and with the 40mm f/2 on the front the whole thing feels like a camera rather than a computer. On a fell walk it hangs off my shoulder all day and I genuinely forget it's there, which never happened with the D750 and the 24-120.
Things I'd change: the grip is shallow once you put anything bigger on it. The 24-70 f/4 feels front heavy, so I bought a small add-on grip and that's sorted it. I'd also have liked the AF point joystick a little firmer, but that's nitpicking. Battery gets me through a day on the moors with one spare in the pocket.
The black and white switch is a toy. I use it more than I'd like to admit.
If you mainly shoot slow things in nice places, it's a lovely camera. If you shoot your kid's football, buy something with a grip and stop reading reviews of this one.