I use the NeoConnect prime and it's fine.
Expect normal cellphone behaviour from the voice service. If you're in a bad coverage area, you will have a bad line. If not, it'll be okay but not as good as a real landline and it will have a small latency.
It's a pretty decent internet connection. I use it on a single computer and it's fast and mostly reliable. However, it does have problems - always Neotel side. These are relatively frequent occurring maybe once a month for a couple hours. So complaining to support doesn't help 'cos the problem disappears by the time they respond.
Their support is quite slow and difficult to contact. However, when you get a response, they're okay if your problems aren't too complicated.
My neighbour has Neotel WiMAX. I would like to get that and downgrade to the most basic neoconnect to keep the voice service + number. It's 1mbps uncapped and works well, apparently. You don't get the ppp problems you do with prime.
However, it's R 1,200 a month. If Telkom's lines worked better in my area, I would rather upgrade to a 4mpbs telkom adsl and get an uncapped connection + number for a bit less.