I have used them and like them, with some caveats.

They are (or at least used to be) made in different sizes. Last trip out, I used the 3" for fishing bluegills in shallow water with a worm on a hook. It took one BB shot and a micro shot below that; more than that would have sunk it. It lands lightly and tends not to spook fish, and it is easily sucked under by shy biters.

A potential down side, compared to many bobbers, is that they don't hold up much weight. That makes distance casting difficult. A long rod and 2-lb. line help a lot with that where one can use them.