I did not do the Great White diving while I was there . Weather did not permit it; however, in South Africa you are not on scuba when you do these trips. You are in snorkel gear. It is not really 'diving'. I enjoyed my scuba diving with this shop with seals and seven-gill sharks very much, so if you can keep in mind you will be on snorkel and keep your mind open to that experience, you should enjoy it. Be prepared for COLD water and some likelihood of weather delays or cancellations. That area of the world has very unpredictable weather.
If you want interact with Great Whites, on scuba, in a cage, this shop does go to Mexico, to Guadeloupe Island on extended liveaboard boat and THAT is on scuba. Again, I have not gone with them on this trip, but many years ago, I worked on a dive boat that went there for the fantastic spear fishing and we had encounters with Great Whites long before there was any cage diving.