Yes, at certain times of the year, with higher demand, QF moves a 744 onto the BNE-SIN route.
The aircraft are in pretty good condition. What class are you flying? The only real downside to the 744s is that the J class beds are the first generation Skybeds (i.e. slightly angled, not fully flat).
But the upside is that QF’s 744s are much more reliable than their A330s!