Unless I'm not understanding this correctly, you're only going to be able to choose which ISP provides your bandwidth - not any of the infrastructure running to your flat (ie: you can't get an ADSL line installed).
Currently - at least for the complex I'm in - the bandwidth is provided by MWeb, so when MWeb goes down it affects me. Theoretically these changes mean my internet connection would "branch off" to another ISP and not be affected (and I could have a different account, with another ISP, in case my main one goes down). There are also restrictions on a local router as to how much traffic it can put through, and during busy times the internet gets slow and packets start getting dropped, long before MWeb is even touched... it seems like this is a kind of throttling put in placed on uncapped accounts (which I have), so I guess (HOPE!) that would fall away and bandwidth restrictions be handled per ISP account, by the ISP.
All in all this definitely sounds like a good thing, but suspect it's still not going to be as good as having a proper ADSL connection :/