Anything below rock solid 30 fps is unacceptable!
Even Bloodborne can be grating because even though it has 30 fps rate as a rule, the frame-pacing makes it jitter at times. Look to the newest Ratchet and Clank by Insomniac for how to create an absolutely gorgeous game, with satisfying gameplay and an incredibly stable 30 fps rate. If a game has a framerate above 30 fps, as long as it's stable, it's all a bonus.
Obviously 60 fps is the ideal and I still believe software-houses should aim for it, making concessions where possible.