It has advantage on enemies wearing metal armour. Most cantrips are this weak, the only exceptions being Eldritch Blast which is stronger because warlocks have only 2 spell slots, and firebolt, which doesn't get advantage on metal. I don't really like casters in 5e because spell caster ability isn't added to the damage of most spells, this is why I play a draconic sorcerer (charisma added to spells of a specific element at level 6). Warlocks get charisma added to Eldritch blast with a class feature and I think one of the cleric subclasses gets something similar at level 8. I think DnD 5e wants you to burns your spell slots quickly, then only use cantrips as a backup. Blue dragon draconic sorcerer (or one of them at least), adds charisma to lightning spells like shocking grasp at level 6, so it becomes 2d8+4 (for example).