plus it worked at 20 below zero
The main advantage was still a round. Overall, comparing to the MP-40 which was the major adversary, PPSh had twice the rate of fire, twice the magazine capacity, some +40% muzzle velocity, was a couple pounds lighter and the maximum firing range was some 50 yards further.
It was extraordinary easy to control, even for women and pre-teens.
I guess all of the above proved to be crucial in Stalingrad.
I don’t know is it a myth or not but it is rumored that the Germans were ditching their guns for PPSh at first opportunity.