From what I have seen the A333 is better on the asian routes than the 763 that it replaces. It can carry a larger payload and seems to have less restrictions. It also seems to burn not much more fuel than the 763 while carrying more. Whether it is better than a B777 I don't know, as these are just my observations from the area I work in.
Another rumour I have heard is that QF is trying to push the A332's on to the RAAF for their tankers, as it is too expensive to upgrade them to the international config.
Overall I think that the A333 is good at what it does (maybe not too reliable) but the A332 well that's a different story.
Cheers Rammel