Austrail Pass?

http://www.railaustralia.com.au/austrailpass.php

Has anyone any experience of this rail pass? It seems almost too good to be true, for myself who plans to A) Travel to Sydney and Brisbane from Melbourne in the next couple of weeks, Travel to Alice Springs and see Uluru and C) get the Indian Pacific to Adelaide and then Perth.

So... what's the catch I'm not seeing? There's a couple of conditions I can't quite understand, and obviously I'm going to phone the number on that site tomorrow, but I was wondering if any fellow boardsies had/have this and would be able to advise if it's the way to go.

Alternatively, anyone know much about the Backtracker pass (http://www.railaustralia.com.au/backtracker.php), and if it's easy to acquire quickly... $217 to get to Sydney and Brisbane over a 14 day period stopping as we please... Having looked at flights and single trip train prices for the last couple of days, myself and the lady are a little taken aback by the promise of this much low-cost wonder, to say the least...