If your opponent has a habbit of not teching and attempting to stand/getup attack in tech-chases, anticipate it and shffl a dair right after your dthrow. If he didn't tech, it should pop him up at just about ftilt height. I trust you know what to do from there.
It's also good on levels like FoD or YS. The low platforms beckon to chaingrab victims to DI straight up onto them. If they do this, shffl a dair onto the platform. You should be able to land the dair before the opponent techs, popping him up for an ftilt or a fair (some foes can even be grabbed again).
As Shack said though, it's pretty easily outprioritised, so don't try to come down on an opponent's head with it. You'll just eat a utilt/usmash.