I was on the SFO to SYD flight just one week ago, traveling in the C cabin. The food was very unimpressive - the choices were the usual crappy chicken, beef or pasta. I would definitely prefer a good restaurant meal over the UA C class meal.
Sitting in the upstairs of the B744 was very nice though. It felt quite spacious, though I would recommend getting a seat forward of row 15 (if you are sitting upstairs) to avoid noise from the gallery.
Have a great flight!