And how will you define an anti-ME3 game from the perspective of ME4?
Significantly less narrative focus. Of course, it'll still be decent, but it won't be where the most resources are poured.
A less defined protagonist. Of course, this also means far less autodialogue than in 3, which even I will admit is good.
Emotional resonance will be weaker. Of course, this also means less contrived forced melodrama. (The overwhelming majority of which worked well on me, but less so on some other players.)
Fewer hours dedicated to the critical path, but a significantly greater degree of secondary content. I do not suspect, however, that said secondary content will be of high quality. In this regard it is not an anti-ME3, except in the sense that missions such as the turian bomb arc and Grissom Academy are purely optional. And pretty decent. To most of us we look at them as mandatory because it's more story, but yeah. Totally optional. ME4, I think, will face similar problems as most more open titles of needing to "fill" all the worlds and doing so without cinematic designers involved, meaning I think most of ME4's side content will not feature an up-close camera.
Combat will be a further refinement and other gameplay aspects will all be solid and usual. I don't spend much time thinking about such things however.
All speculation, obviously.