The IQ was excellent. I missed some shots as I was just learning the Liveview autofocus system and the subject was rarely still, but the in-focus ones were up to standard.
The downside is that resolution is reduced to 1920x1280, which If I have done the math right is about what I got from my D1 & D1H bodies. With them I learned to shoot tight since there was little margin to crop in post. Same with the D4 silent mode, must get the framing you want before taking the shot.
Silent mode is not something I would use unless necessary, but it is great having it available.