I'm 5'2'', so not sure if there is enough room for this to be useful for taller people, but for us shorties with feet that don't fully touch the ground, this is a great solution to comfort on any flight!

There was not enough leg room on the plane to actually stick your legs through the sling as shown.

There is so little space between the seats that I didn't feel like I had much room to elevate my feet.

Considering the shrinking space between rows of seats in airplanes---there is NOT ENOUGH ROOM to use this gizmo unless you are traveling first class, in which case you wouldn't need it

it can't even be used with in coach seats, not enough room

I didn't have enough room to put this on my calves as in this picture but more of a step stool position