I like them they are good eaters of dead plant material and help keep glass on a tank clean. Can have spots which look cool too.
That said, many people find them a curse. Not me.
Not to offend lovers of all life, but they can be squished and fed to bottom feeders, and meat enjoying fish. A way to keep the circle of life going.
Loaches will often eat unwanted snails as well, no useful, circle of life/ barbaric squishing required.
Usually if you have harder water and over feed they will over breed. They breed based on food availability - more food, stronger healthier snails, more breeding, more snails.
They can get larger, maybe half inch or so possibly. In my pond I had a couple larger ones, half inch usually, one made it to 3/4-1 inch.
Do you like it?