I did a BA LHR-SIN-SYD in Y class a few years back, and going out it was quite nice - but then I had two seats to myself, and PTV.
On the way back we were unlucky and had one of the oldest BA 744's which had not at that point been reconfigured, so it was "main screen" movies, and I was a gentleman and gave up my aisle seat for an elderly lady whose seat broke, and wanted to be seated with her family. I ended up in one of the middle seats - quite possibly the longest/worst flight of my life ever!
On the positive side, I was able to blag lounge access at Sydney, but boy that was a long day.
So long as I get a PTV and an aisle seat I would do it again in Y though.
I'm off again in Feb, but have been fortunate enough to be able to afford Upper Class tickets on VS this time around
Rich.