I just was in 4D on FLL-LGA -- very nice seat with good legroom. Worth $39 (including priority boarding)? Eh, maybe. As mentioned, the fixed armrests could make it a little tight in the hips for some. I think if you're under a 38" waist it'll be fine.

What really shocked me about this flight, sitting in that seat, was how AWFUL the first class product/experience looked. I can't speak specifically to FC seat comfort, but the seat backs were thin, the pitch was relatively tight for FC, and the TRAY TABLES WERE IN THE SEAT BACK IN FRONT OF YOU. In first class! Really tacky. Like I really enjoy having my seat banged by the person behind me opening and closing the seat back tray.

And then, the catering appeared to be a measly snack basket with chips and some bananas. On a 1:30pm flight, which should be within a lunch window on a 3-hour (blocked) flight. On my way down, AA served a choice of salad with salmon filet or chicken wrap on a 3:30pm departure, well outside of meal time.

There's no way I would ever pay for FC on DL on this route/aircraft.

I'm doing JFK-SLC in FC soon on a 738/752. It had better be better than what I saw from FLL, or I'll be pi55ed!