Good, but it depends
Bought to use occasionally for a bit of freedom with my 19kg hunting-type dog who's still in training and doesn't have a perfect recall. He's not aggressive and so far he's never lunged while the lead was locked. It's true that sometimes the tape gets twisted and doesn't retract, and if I need to be sure he's only a few metres away, I just hold the tape in my hand. For what I need, it's perfect.