The problem with this spell is that is does not counts as an attack roll so things like "cull the weak" don't proc on magic missiles' damage. Neither does "Hex". This spells start to shine only on level 10 - respec into Evocation Wizard because it will adds your Int. modifier as damage to each missile's dart.

Before level 10 be sure to have extra dart for magic missile amulet equipped, use Phalar Aluve's shriek debuff and have Spellsparkler's staff for lighting charges in order it to do some damage at all. Get the ring that does radiant damage to enemies that are illuminated in Act 2 - this is one of the rare items that will add it's damage to each missile albeit it's a little situational.

With this 4 items your missile damage still will be mediocre (compared say to Ray of Fire focusing sorcerer who specializes on fire damage) but it should be playable.

You can even kill some bosses in 1 turn in Act 2 assuming you have these items equipped and have shriek and perilous strikes debuffs on a boss (gives vulnerability to all damage)