I haven't flown this route in Y- but I have in Y+ several times. Overall it's actually fine, and surprisingly I have been able to sleep about 7-8 hours each time though not all at once.

The quality of the food is bad though and the quantity is very small. But I still prefer the extra legroom on UA Y+ compared to SQ Y. But seriously, it's much less food than you get on BA in Y on LHR-SFO which is six to seven hours shorter. And also worse quality.

My tips: Bring at least 3-4 Kind or Lara bars, a large water bottle, and toothbrush /toothpaste. The snack bars are essential to prevent starvation but are tough on teeth so I brush about 3-4 times over the course of the flight.