If you happen to have a well behaved DF then it really does shoot just fine once you get the hang of it.
AF is if a bit vague and I have had my body tuned up ay mac. After that tune up, it has been humming along just fine.
What would make me happy is more AF points like one up around eye lever shooting a full length and portrait 9 would do nicely, one with options for the weird bracket which did noting good, is just funky.
Speed would be good too, but that would need more horsepower in the motor I guess.
I really need to see some details to figure this out.
As for reliability I can think of a few things that could be better like:
focus motor run-away
locking up with the shutter open.
At least with the DF they fixed the rubber coming off the grip issue that I had with the AFD