I don't know. It could be a great thing, or it could be crap. It depends on the "details", how well it is executed.
I've driven a few cars with back-up cameras that activate when the car is in reverse. A lot of the time the camera lens has dirt/snow/water on it, rendering it useless. And it's only a tiny lens. One drop of water can totally ruin any visibilty. If Nissan has found a good way to keep it clear, excellent.
In addition, your mirrors give you a "framing reference". I can see the edges of the rear window pillars, roof, etc, giving me a view of what's behind me IN RELATION TO THE CAR. Without that, I just see a picture of another car, which I can only assume is SOMEWHERE behind me. But I can't tell specifically where it is. With a typical rear view mirror, I CAN tell.