Cape Town is very much an vibrant city that looks/feels like any other western city. There is this prospection that Africa isn't as 'developed' or 'modern' as other continents. But honestly, South Africa has the same kinds of malls, 'organic' food stores, technology, pop cultural; essentially everything you find at your home can be found there as well. The biggest difference you notice right way once you arrive is how unfairly distributed these 'developments' are. My program director put it perfect, she says that South Africa has one leg in the developed world and the other in the underdeveloped world. (I recognize that the terms 'developed' and 'underdeveloped' aren't respective of the country's growth in other areas and seen as disrespectful to describe countries as such, so please disregard my lack of a more appropriate terminology.) But yes, the divide is very prominent.
Anyway, Cape Town was still incredible as it has several attractions to keep you busy for weeks (seal snorkeling, paragliding, hiking the three mountains there, festivals, the wine country, SO MUCH FOOD, the two oceans!..). But there are also various communities available that host cultural events for study abroad students (traditional Xhosa dinners, attend a famous braii restaurant, visit Nelson Mandela's home and IES even organizes homestay weekends) that allows you to experience the rich customs of South Africa. So if you are an adrenaline junky or inquisitive butterfly, Cape Town provides a lot of options to explore.
In terms of safety, it is simple: don't do something in Cape Town, that you wont do in a big US city (like NYC). Theft (pickpocketing especially) is a common crime in Cape Town and it happens because you're not aware of your surroundings, walking around with your Iphone out, or not properly putting your things away. Some friends of mine had their things taken because of these reasons, but it didn't happen to me because I tried to be cautious when I was in public streets. The IES program provides a lot of info that address how to protect your stuff and it really helps if you follow those rules, nevertheless they are available in case it happens to you, so don't worry too much!