I've flown JFK-SYD on MU before, in coach. MU's economy isn't bad, it's not as a good as an American airline, but it's not as bad as others make it out to be. Maybe I just fly coach and my standards are a little lower, but I digress. The FA's don't have a good grasps on English, it's mostly words like chicken, shrimp, water. Ask for a napkin to clean up a wine spill and you'll get an extra blanket... The movie selection is limited, but understandable for being a Chinese carrier.

As for the price, when I flew it was $550 on MU, but took 49 hours there and 51 back (JFK-PVG-PEK-NKG-SYD vv). Pretty sure I took an extra leg for the extra MQM's though. If you can avoid MU's A330 do it. I hated that plane from PEK-SYD. On the A330 the last half hour of the flight is a video that you can't turn off of meditation and tai chi, absolutely awful. The 777 doesn't have that and I would imagine the 787 doesn't either. I really liked the flight times in that I arrived in SYD at 8am.

If you have Priority Pass, SYD has some cool restaurants that are participants. The MU Lounge at PVG isn't bad, plenty of reviews on here of the lounges.

If memory serves me correctly, they do offer paid upgrades at check-in. MU doesn't have OLCI, you have to do it in person. Without SP this would easily be like checking in for a Spirit or Norwegian flight.