I've personally used pepper spray 4-5 times, and the department as a whole considerably more than that. In each case, the individual being sprayed stopped what he was doing (resisting) and gave up.
Of course, we are concerned with arresting this individual.
From a civilian standpoint, all you really need to do after spraying an attacker is leave, and an attacker who is essentially blind is unlikely to follow you. There are guys who will tell you that bad, mean people can "fight through" the pepper spray, (and if you're already in grappling mode I can see that) but for the most part it's going to be "spray and depart."