Yes, magic missiles automatically hit. I lost my first character, Tormyr the shiny lawful good paladin, to a group of level 1 wizards in training. The wizard school had turned evil and started blowing up parts of the town and we were sent to investigate. We approached the tower and saw a group of 10 students led by prefect going into it. The students looked scared, so my paladin stepped out and tried to talk to the students to see if they were in need of help, what is going on in the school, etc. After a bit of talking, the prefect shouted, "Now!" 11 simultaneous castings of magic missile hit my level 4 paladin for 110 damage. Wrote up a new character that had the Shield spell.