Haneda is convenient for getting into Tokyo and Yokohama area.
One problem, is that the slots for international flights are quite restrictive. They seem to allow arrivals, either VERY early, 4 to 5 am or around 9 to 10 pm. The departure slots are also quite restrictive.
This may change as demand grows for this service.
If QF get decent slot times, it may well prove to be a popular flight for them. Hopefully they won't let J* do the Narita flights.