I don’t find the FTZ adapter to be a practical limitation in my shooting. It is small and light — 4.8 ounces. Works with all my F mount lenses.
Steve has noted that the FTZ can slow autofocus when you are trying to go from minimum focus to infinity or from infinity to minimum focus. I find that in shooting, I am almost never doing that, so it has not been a problem for me. I have used the 500 mm PF, 300 mm PF, 70-200 f2.8E, and 70-300 AF-P FX lenses extensively on the FTZ adapter on a Z7 and Z6 and now a Z7II and Z6II. I have not found focus speed to be an issue. I have tried the 200-500 mm lens on a Z7 and Z7II — I tend not to use it that much because it is heavier and I have the 500 mm PF. It focuses fine, although it is a bit slower focusing to start with, even on m,y DSLRs (which I still have).
The FTZ does not provide autofocus for screw mount lenses. I have only one (the 70-180 mm micro Nikkor zoom), so it has not been an issue for me. You can still do manual focus with screw mount lenses and the Z bodies have a number of aids for manual focus.
Some third party lenses may have AF issues, but that may be fixable with lens firmware updates. If you have or would get third party lenses that you would want to use on the FTZ, it’s worth checking into.
The last thing I recall is that the FTZ may not pass through some of the information on the lens to be recorded in the image file with certain older manual focus lenses. I have not noticed that, but did not look. I have used the 19 mm PCE lens on my Z7 and Z7II, but it’s not older. Might have the issue with my 105 mm f2.5 AIS lens.
All this said, I generally prefer the Z lenses where available. They have been anywhere from very good to outstanding and generally better than their F mount counterparts optically. I am looking forward to Nikon getting out Z mount telephotos, particularly the 100-400 mm. And I’d love to see Z mount PF lenses, but they are not on the roadmap yet.