1a rope you do not have to carry
One use gets you a tall climbable column out of nothing, and you can set blocks against it while you are on the way up. Alternate between the flute and a handful of platforms and you can reach the top of the world early, without hauling rope or waiting on a hook. For sweeping the sky in search of floating islands before you own wings, it is the fastest tool available.
it only goes up
The pot refuses to appear off screen, so you cannot drop one into a shaft below and ride it down. It also gets blocked by anything between you and the cursor, which means tall trees, cacti, background clutter and other pots will shove it somewhere you did not intend. Expect to reposition before it lands where you wanted.
lava is the one place it beats rope
Ordinary rope will not sit in lava. This will, so it doubles as a way to climb out of a pool you fell into or descend a wall next to one without touching the surface. Worth keeping in the hotbar on any deep dive for that alone.
do not count on it in a fight
The wind up is among the slowest of anything in the game, in the same territory as the mirrors and conches. By the time the snake is standing, whatever was chasing you has caught up. Plan the climb before you need it. The whole thing also expires on a timer, so a long build session means summoning several.