I've just been up to Japan on Air NZ (787). The past couple of years I've been lucky enough to fly Premium Economy, but this year it was Economy both ways (got a sky couch row, which while I couldn't use the service the seat pitch is a little better than the normal Economy seat).
The seat and roominess were fine. Sure PE is nice with a better selection of food and better service and more room, but from my experience I can't see the justification for spending so much more in PE (unless I'm not paying.....).
It's only 11 hours-a lot of us sit in a far more uncomfortable chair at a desk for 8+ hours a day for years on end.............