There are a few elements in this question.

In reference to Rhodesia/Zimbabwe and South Africa, the question rests not on the 'removal of apartheid', but the system of government that replaced it. In a sense, it would be like asking: was the throwing off of colonial rule for the United States and Haiti a disaster. Well, they both overthrew their colonial masters, but they have experienced very different histories and were different nations from the beginning.

The largest problem with the governmental transfer of power in Rhodesia was its one party monopoly run by a man who was violently unstable and manipulative. Mugabe never had the ethical capacity to seek to create a robust and functional state, he has always been focused on power and makes decisions on the basis of vengeance. Per his famous remark, he has a number of university degrees, including a degree in violence.

In the same manner, South Africa had a very different history. First, it enjoyed a highly developed infrustracture and a stable middle class. It also enjoyed a negotiated peace in which the losing side still retained a great deal of military force. Further, and most crucially, it had a political leader who recognized the need of maintaining a functional and stable and democratic state.

I have lived in South Africa and really enjoyed it. Before going, I thought it was probably a place of danger and decline. Once I lived there, I saw just why many white South Africans that I had encountered in Europe and the US would go home after spending a few years in London or New York. They missed their homes and I could see why.

South Africa is a stable state. Poverty is a problem, crime is certainly a problem, but people who treat South Africa as some kind of a disaster for all white people either is lying or living in a past that romanticizes apartheid.

If I were you, I'd suggest you actually try to read South African newspapers on a regular basis, watch South African television, etc. you will get a sense of the country as its discussed by its people, and not rely on sensationalist headlines from white supremacist websites.

Our economy and currency was in a better state during Apartheid. However the currency being just as strong as the dollar (and at times even stronger than) can be attributed to being an English colony and therefore using the pound. When the rand was hailed into existence it's value was based of the south african pound which was naturally strong.

Since our rand started at a very strong standpoint and our country was about to go into a turbulent future filled with uncertainty and sanctions it's only natural that over time the rand would decline over time. So whether or not Apartheid ended the rand would've gone to shit due to increased sanctions and trade restrictions.

In terms of the economy our economy was indeed strong during Apartheid. But this is because of 2 reasons

90% of the population (non whites) was used as cheap labour by the white majority in power. This naturally can make any economy powerful

Secondly the government didn't need to take good care of the whole population in terms of welfare, health care, grants etc. The government had lots of money to spend on other aspects of governance as it neglected most non-whites from their budget essentially