I also use Vodacom 3G. My ping hovers around 700 with the lowest being about 450. You do get lag spikes, although it isn't as common as it was 6 months ago.
I don't have any problems playing between 5pm and 8pm, so I think it has to do with area. I do have some problems on Saturdays and Sundays during the day.
There is a problem with the connection resetting sometimes, but it doesn't happen often to me. Getting it fixed is sometimes problematic. Sometimes I can just disconnect and reconnect from VMC. Other times I have to unplug the modem. Sometimes I have to restart my pc, but that usually happens if I've been playing for most of the day or my pc has been switched on for a long time.
In short, its acceptable, but there will be times when you will be swearing at Vodacom because you can't play.