It should be quite interesting to see what develops in the longhaul market in the coming couple of years.
I'll be testing air asia's PER-STN-PER services in July and again in November, so I should be able to make a fair assessment of the air asia longhaul experience. Already a couple of negatives come to mind: 1) Flights land in stansted and coupled with the arrival times of some of their flights this is very inconvenient (as bus and train services don't run late into the night, leaving you with a 70 pound taxi ride to central london. 2) Their fares are most competitive relative to legacy carriers ex-Perth (great for me). I haven't checked recently, but I remember comparing PER-STN with SYD-STN and the difference exceeded a QF Y ticket between PER and SYD.
The inconvenience is not really an issue for me, I travel with a few other people so for about 20 quid each we can get a driver to meet us at Stansted and drive us to our london hotel in an S-Class Mercedes. And, living in Perth the value proposition works for me.
But the proof of the pudding is in the eating, so I'll have to wait and see!