Huh! I've flown Premium Economy with a few European carriers (Air France, KLM and two others I believe?) and didn't notice anything different. Food on KLM/AF is always good though. I've never flown Premium Economy in Lufthansa or SAS (as far as I can remember.) And I've never seen a duvet on a plane even in first class! Are there actually airlines with duvets or just nicer quality blankets?

The differences I've mainly noticed in premium economy are: electrical outlets, nicer in-flight entertainment, more legroom/better reclining, nicer head cushion, closer to the front (if that's a benefit) and that's about it. Amusingly, I've found on Delta the "premium economy" section occasionally extends slightly outside, e.x. the electrical outlets and better in-flight entertainment (but not the legroom) aren't only for premium economy but also 2 or 3 rows of normal seats beyond. Which is a little strange, since I would think Delta would use the opportunity to present that as an upgrade (paid, or free as a goodwill gesture) but I've only ever seen them labeled and sold as normal seats.