I imagined I would be among the very last to experience these seats... but April 16 2007, AA83 ORD-SFO had the NGBC, and we had 5A and B.

The good: infinite seat positions, including forward and aft; accommodated me supine or on my side, even with 6'4" / 193 cm with no problem, though the "foot box" was kinda cramped; the usual buttons are in a very easy to use spot, and the audio plug isn't that difficult to locate (on the vertical surface below the grab handle on the privacy screen.) I never felt I was sliding down at all - maybe a "YMMV" thing for the name "wedgie seat" to fit, because it certainly wasn't that to me.

The less than good: the lack of room for much in the way of carryon at, or under, the seat, other than a few books, etc. But I'd much rather have the seat and use the small mid-cabin bins for lighter stuff. And for a window passenger, it is a bit of a climb over a reclining aisle person. The side bins will take even the large max allowable carryons, but you may have to position them wheels out, making them a bit more difficult to handle.

My take: for a tall person, I prefer these seats to IB or CX. Far more good than bad.

I wish I had checked the reg / tailcode, but we'd arrived from NRT and connected, so by the time we waited over 20 minutes for a gate at SFO and disembarked, I forgot to do more than bail.