According to seatguru, the Turkish Airlines 777-300ER V2 has "28 flat bed seats with 177 degree recline". Maybe flat-ish, but that sounds like it does have a bit of an angle.
I would say that the difference between the two configurations in J looks like a lot more than just 3 degrees of angle on the seats:
In the V2 J cabin, the seats are 2-3-2 and straight across (which is the same configuration they have in Economy Comfort - though I'm sure the seat itself is not the same).
In the V1 J cabin, the seats are 1-2-1 across, angled, in semi-private pods. Looks like lots of personal space. These seats (the seats themselves, as well as the space they occupy) do not look at all like the J seats in the V2 J cabin.
From looking over the photos of these seats on seatguru, I'd say the V1 seats look GREAT - competitive with the best of today's international J seats.
The V2 seats look mostly OK, but clearly not top-notch. It looks like the seats themselves are about the same size (22" wide, with 78" pitch). Not sure about how much one might notice the slight incline on the V2 seat when flattened. The obvious difference is in the degree of privacy for each, and aisle access. Each V1 seat is in a semi-private section, separated from others by a partition. The V2 seats are completely open - no partitions. Then there's that middle seat in the V2 configuration...I would be pretty bummed if I got stuck with that.
I'll be traveling with my spouse, so if we had the 2 seats on the outside, we would not mind "sharing the space" so much, and we could certainly manage access (after both had gone flat/to sleep, climbing/jumping across to access the aisle). But in my experience that requires some acrobatics and almost always wakes the person trying to sleep in the aisle seat, so it's not optimal. If we got stuck in the center 3-across seats along with a stranger, not so great. Yeah, I know, first world problems...
I'm currently "shopping" for which flight to take, comparing multiple airlines and different J products, and for me there are other factors in the mix besides the quality of the J seat. That said, at the top of my priority list is getting a good, solid night's sleep on this very long flight. I do not sleep easily on flights (or in anything that moves) so I'm looking for an environment that is well optimized for sleeping.
I'm guessing that I could probably get some good sleep in the V2 J cabin here (as long as I'm not seated in that very wide-open middle section, where I'd expect to be disturbed frequently). The two seats on the outside (the window-side of the aisle) would probably meet my expectations (although I would much prefer the J seats on the V1 planes!).
How reliable is Turkish Airlines about allowing (and actually honoring) seat selection? I would not consider this flight if there was much chance they would randomly seat me in the 3-acress middle.
Thanks for all the input.