I bought a tub of Slug Gone last year, can't remember if it was at Tatton Park or Southport Flower Show and used it on my hostas which are in pots.
Just sprinkled lightly when the first sign of growth came in spring. It swells up quite a bit when it gets wet and forms a hairy layer on the surface (smells very much of sheep doo at first).
It did what it said on the label - slug gone. The first time ever the hostas haven't been shredded and it is also slow release fertiliser, so haven't fed them at all this year and they are still looking pretty good.
Also used it on dahlias and cherry tomatoes in pots and it has been pretty good there too - though a few snails seem to have had snacks on them. Not sure how the snails get across to the plants - I think the buggers have pogo sticks!