I'm not surprised by the negativity. The F90 was bound to ruffle a few feathers given all the traditional non-M features such as xDrive, no MT option, torque converter automatic, etc.
For this class, I believe M did what it needed to do to be competitive and stay relevant. The engine characteristics/output essentially demands AWD, and at least it's rear wheel biased (and can be turned off). And the fact that it's lighter than the F10 despite being bigger is a nice surprise.
Still, I am kind of melancholy when I reflect how different this car is to my E39 M5 (MT only, RWD, naturally aspirated V-8)...no matter, I am definitely not the target audience for this car.
And it is of course a tradition with every new M car to bemoan the death of whatever feature the preceding car had that the new one doesn't.