That depends on how intelligent the enemy is or whether they are running after knocking you down, and you want your movement to catch them, or they move on to another target, if your group has the enemy outnumbered. Again, think about, say, a Jackie Chan movie, where it is him against many enemy fighters at one time. He does not just stand there and beat on the one he knocked down. He moves on to the next target and knocks that one down and then the next and so on, until they have all been knocked down enough times that they do not get back up again.
If I am running a game where your party has surrounded one or two main enemies, if one of them knocks you down, they are going to switch targets right away to avoid getting hit in the back or something. So your character could spend the round crawling back to his feet or happen to have this feat and bounce right back up and maybe even get an attack at advantage on the enemy who is no longer facing you. And if you are a thief with this feat, that could become a backstab.