A few years ago, I brought a few bottles back from a trip to South Africa. I enjoyed a couple of those last night. They were the 2000 Thelema Cabernet Sauvignon and the 2000 Rust En Vrede Cabernet Sauvignon. These two wineries would be regarded as amongst the leading ones over there.
Both wines taste of blueberry and blackberry fruit, cassis, and a bit of mint. The fruit is still lively and the wines are well structured. Probably the major characteristic is the earthy finish - not everybody's cup of tea. But this gives them away as South African.
The fruit of the Rust En Vrede is perhaps not quite as rich and the wine is quite tannic, perhaps a bit harsh. Overall, I would probably place their quality as middle of the road Coonawarra or second tier Margaret River. If you want to try South African wines, I remember Kemeny's in Sydney used to sell them.