I tried Premium Y for the first time two weeks ago SYD-BNE. The seat wasn't converted when I boarded and when I asked the FA whether he could convert the seat for me he said "it isn't allowed". When I pointed-out to him that I had paid for Premium Y he rolled his eyes and said "Well, no-one bothered to tell me!"

Anyway, he then converted the seat but to be honest I wouldn't bother paying for it again. IMO there's nothing particularly "premium" about it at all (even with the free food & tv).