On my car the camera is placed such that it rarely gets blocked by dirt or debris. I sometimes flip back to the mirror only to find I can't see anything due to dirt on the rear window. Flip back to camera and I see just fine.
I can't see shit out of the back window without some work on my part on many cold mornings (with electric defrost), but a tiny little camera-heater could be both fast and efficient (which is more important for EVs).
I can wipe a small camera lens off faster than I cash wash a uselessly-filthy back window enough that it is better than a streaky opaque mess, as I've had happen to the back window on fairly mundane (if long) road trips with regular road grime.
Fewer windows means a cooler interior when it has been baking in the sun
It's a lot harder to get distracted by light and glare from phone screens or whatever that back-seat people are using when there's no interior mirror pointed in that direction to begin with
It doesn't sound all bad. And since it's got rather good cameras, that sure does sound better than the vehicles I've spent time driving that had neither rear windows nor any cameras.
I can't think of many real negatives. Since I got a parking camera in my car, I don't use the rear view mirror at all during parking. If there is some way I can get more accurate information about the blind spots around my car (and this camera seems to be one such thing), I'd much prefer that.
There will be cleaning and electronics problems but every technology comes with its own set of issues. The only thing I can think of is the general idea that low tech. often has less moving moving parts and is more resilient but I'm not sure that applies here.
Subaru does it this way. The rear window defrost has a higher density of heating wire around the camera, so on a frosty morning, it clears up very fast