UCT is arguably the best university in the country / continent and UCT GSB is among the top bschools as well (the others being UP GIBS and Wits BSchool). That being said - Cape Town is one of the best locations you can possibly find anywhere.
As for job opportunities in SA, it is somewhat limited. From my experience, an MBA is not such a big deal there, with lots of people in management roles who have grown into them but with engineering/finance backgrounds.
Also, due to economic empowerment legislation, every medium and large company in SA is heavily incentivized to hire a local before a foreigner, including into management roles.