I've had a very good experience so far. If you schedule your heavy downloading for overnight and don't rape it during the day it will work out really well for you.
Speeds are excellent. They recently changed their throttling margins based on your download behaviour. I got throttled one month at about 115GB (1Mb/s line), browsing was fine & I could still download at 45KB/s. I changed my download behaviour after that and after 100GB I'm still in the green, have not seen orange (warning) or red (throttled) yet.
its nice that telkom tells the clients with a graph u been throttled or not either green or red then you can work around it and never be throttled