I just initiated a purchase and am waiting on the text message to my phone. I'm not sure if this is a problem with their service or if it's just my provider being unreliable as it sometimes is, but hopefully it'll come through soon.
One disappointing thing is that the Australian price is $2.55, despite the current exchange rates being almost dollar-for-dollar. Maybe there are other reasons for this but it'd be nice if they could be a bit more current with their price matchings. Of course I don't mind paying an extra $2 but that could possibly be worse on pricier packages.
Overall sounds like a cool idea though! I just hope I'm not inadvertently selling my soul to these Zong people.