I wandered down to have a look at the Premium Economy cabin on my flight from PEK last week. As there were only three people in the cabin I tried out the seats, and I was very impressed with the comfort and quality, which were wider and with more leg room than what I originally expected. As I only sat in the seat for 10 mins or so, I have no way to tell if the seat remains comfortable.
The noise cancelling headsets and AVOD were of excellent quality and I agree that the manual seat mechanism is a bit loose.
It is very much an 'Economy plus' rather than a 'business minus', but for a day flight or a short trans-atlantic night flight it could be an excellent compromise in my opinion.