It's complicated. He was certainly one of the key catalysts for change, but he did so in the face of massively mounting international pressure and sanctions, and he was widely disliked by both whites for making it happen and blacks for not doing it earlier or quickly enough.
What is inarguable is that he was the man who freed Mandela and in doing so made the ending of apartheid unstoppable.
de Klerk is basically Gorbachev. True believer in the system that was sort of forced to change it, kinda sorta realized the system they were supporting was fucked but too ingrained/old. But he was also behind atrocities like the Craddock Four.
Ultimately I do think it's harder than given credit for to dismantle such systems and to get the Nats to lay down arms (even if things were trending in that way) and for that he should get at least some credit.
