A bit more on the new Y+ seats, based on my trial onboard D-ABYQ on Thursday:
The new Y+ seats (manufactured by the company ZIM Flugsitz,
http://www.zim-flugsitz.de/zim-flugsitz/) are definitely as step up from the normal economy seats. They are about 3cm wider (which doesn’t sound like much, but it is quite noticeable after moving out of a regular Y and into a Y+ seat), and they have 18cm more pitch. You get your own (reasonably generous) armrest, a small space for setting a glass, and a generous table that folds into the armrest, and a slightly larger IFE screen in the seatback (30cm vs. 23cm in regular Y, except the front row, which has a fold-away 23cm IFE screen just like the exit row seats in Y). The front row also has an extendable leg rest which I am sure will be appreciated when trying to relax sleep on the longer international routes.

Y+ seats: 8 across instead of 10 across allows for individual arm rests and a wider seat. (Compare to regular Y seats directly behind—there is only a hard plastic screen that acts as an optical partition above the seats to divide the cabin—Y+ is not partitioned in a separate cabin)

Y+ seat as seen from first row of Y: between the seats is a holder for two 0.5l water bottles. The IFE screen is a bit bigger (30cm vs. 23cm). The foreground is a standard Y front-row screen. Note: there is also a lot of extra room in the first row of Y, and these seats will be subject to a 50/70/90EUR upcharge. I am not sure why, but a few of the last row of Y+ seats also had a Y+ IFE screen useable by the Y pax behind. If that was planned, it is a nice feature for 4 of the pax in the first row of Y.

Here is the Y+ seat fully reclined. If you can sleep in the C seat in the “cradle” position, I am guessing you can sleep in these seats with similar quality. However, you will never mistake the Y+ seat for a C seat when fully reclined, be it sloped or flat…
One thing that bugged me somewhat (which we discovered with
rcs85551 playing the role of the obnoxious brat child or rude passenger grabbing and kicking the seatback) it that the seats have quite a bit of “play” when they are reclined, and when they are bumped from behind, your head will tend to get launched forward. This will be annoying when it happens while sleeping.
Another step up for the premium economy product is electrical power: AC and USB power sources in every seat(!), and the seat I had didn’t overload when I plugged in my 85W Apple power supply and connected it to a dead MacBookPro (!!). That alone is to me almost worth more than the old C seats (which tend to crap out at load of about 55-60 VA IME) to me on day (westbound) flights. By comparison, the latest version of the Y seat shares power with every 2 seats, which is nevertheless still a step up over no in-seat power. I only noticed USB power, however, I didn’t pay much attention to the regular Y seats, and the information in the press kit implies that there is also shared AC power in the new Y seats. (If someone could report whether there is AC power in regular Y on the 748, I would appreciate it. I did not notice/verify one way or the other)
Each Y+ seat was stocked with a 0.5l water bottle, and a space to keep it during the flight.
Premium Economy passengers are also provided with an amenity kit in a slot in the arm rest, which contains:
• Pair of socks
• Eye mask
• Earplugs
• “Erfrischungstuch” (a packaged wet “towelette” for hand/face washing)
• Toothbrush
• All packaged in a flat half nylon/half scrim bag suitable for carrying small flattish items.
The catering service was also on display in the front of the cabin. It looked to me like the normal Y food, but served in ceramic service:

Dinner service.
As I pointed out before, you get a nice fold-out table in your arm rest that leaves enough room to eat and/or work. One has to be a little careful in case the person in front reclines unexpectedly, but even with the seat in front fully reclined, there is enough room for dinner service or to work on a laptop.

Table taken from front row of Y+.
Overall, it appears to me the new Y+ is a decent addition to the on-board service, but it will be a quite personal issue to decide how much of a premium it is worth. For those who are condemned to fly economy, it is worth checking out the service at least once and deciding one’s self how much some extra space and a slightly upgraded soft product is worth to you.