From what I had heard, it was a retrograde law only enacted after the Empire lost control of the place. I have also heard that even under that law, Black South Africans had more economic opportunity and freedom than most of those living in other African nations... but that's more of an indictment against places like Uganda and Nigeria than anything else.
Honestly, it was a dumb
thing to do, and it even divided English whites against Boer whites, politically. It was also bound to fail in the end as well as leave the half-castes in a terribly isolated position both during and after its run.
Hell of a job, all 'round.