On the upside, row 12 is the best middle seat of any premium economy seats you can get. Yes you'd be stuck between two people, but at least there's no one reclining in front of you. You can even get out and go to the bathroom without bothering the people next to you most of the time!

With the double armrest and extra space all over, I would take a middle seat in row 12 over a Y seat ANY DAY.