Icons look swish and they can convey personality. Trouble is, they come with a boatload of subjective meaning. Without accompanying context or labels, each icon could mean something entirely different to different users.
We’ve seen them used in isolation in areas as important as navigation bars, forcing the user to guess their meaning.
Always use at the very least a tooltip, or accompanying text label. Icons should never be the sole reference for any action. Instead, use them to reinforce the action.