I was on a NW D93 from DTW to MDW last month, and the F seats were cloth, with thinly padded headrests - you could feel the metal seat frame hitting your head - far inferior to any F seat I've ever experienced on CO.

Also, when the FA came down the aisle with a cart (?)offering beverages, I aksed for coffee, and was told that, due to the short duration of the flight, they didn't make any, so could I pick something else! This was a 55 minute flight - even SW offers coffee on shorter flights - and in coach! Not impressed with NW F at all