I’ve flown this on VS premium economy (SFO-LHR-JNB). I was able to build in a 23hr layover in London though so got to do a little sight seeing in London to break up the trip. I didn’t find it too bad — seats were comfortable enough and I wasn’t dying at any point of the flights. I fly about 100K miles a year and probably do a 50/30/20% split between biz, economy and premium economy to give you an idea of what I’m used to flying.