I've grown it for the last two years. Last year the yield was low but enough to give me enough material to plant a bit more this year. I now have three healthy looking plants which I hope to harvest just before the first frost. So I don't yet know how substantial the tubers will be.
I don't recall any slug damage last year but generally I'd say the jury is out as to whether the yield justifies the effort (which isn't great) and the space taken.
Janet G