Flew IAH-LHR and DUB-EWR in PP for the first time last month.Got the seats with award upgrade miles. Absolutely felt it was well worth it.
We were in bulkhead both ways - aisle and next on the center 4 across to LHR, middle on 2-2-2-DUB-EWR. DH has mobility issue that requires using a walker and the seats were great. In the bulkhead aisle seat he was able to get up and get to the nearby restroom without major problem. Having spent many flight hours in the Polaris cabin, I find seating there to be rather coffin like when reclined, and DH would have difficulty getting into and out of the Polaris seats. Ergonomics of the PP seat were great - once I figured out how to use the three positioning buttons I actually slept for 5 or so hours, which I rarely if ever was able to do in Polaris.Pillow and blanket definitely upgraded from Y. Meals were served on china and seemed upgraded from Y - decent food in reasonable portions. Earphones provided were decent - not Bose noise cancelling class but quite good for a plane. Video screen larger than in Y for sure. Little amenity kit had essentials like eye mask, socks, lip balm, etc.

As a diligent squeezer of nickels 'til the buffalo farts I'd not likely go for a $4K upgrade, but for a few hundred bucks or fair number of award miles, sure, I am all in.