Shorter load times are impossible to argue with for me. That's the hands-down winner for most positive "new feature" for my taste. Runners-up include ray-tracing and even better controls.
Yeah, nothing announced about the PS4 so far to me really suggests more, in substance, than improved efficiency all-around, but frankly I'm a pretty conventional gamer in the technical sense, so that's really the main thing I'm looking for anyway. I don't need a lot of gimmicks.