very happy with my iphone 4 from Voda.
I use a Telstra prepaid sim for the occasional time I'm out of Voda's coverage.
I can't believe how bad Telstra are to deal with for simple matters, but admit their coverage is excellent. It's funny checking email 7000' over a vast outback salt lake.
The NAIPS App for iPhone is outstanding. Well worth the (tax deductible) $9.99