I fly QG Y+ quite often and have done VA Y+ twice (over and back to LAX) and was underwhelmed.
Seat is not a patch on QF's Y+, neither was food, neither was service (friendly but distinctly amateurish). T3 at LAX is really awful as well and if something goes wrong with the plane, GOOD LUCK as they dont have many others available to sub in.
Having said that it was cheaper than QF Y+ at the time. I would only do it again if the price was SIGNIFICANTLY cheaper than the QF equiv.
Cheers
Timmi