Dave there is a fairly comprehensive review of it vs the Virgin travel card here
http://www.ausbt.com.au/travel-money-cards-compared-reviewed-qantas-cash-vs-virgin-australia-global-wallet
No catch but don't try comparing it to points that you would get from a normal credit card. It does make a good OS travel card.
I have one (doubles as my Qantas FF card) and so I'm thinking of loading it with Yen for Japan