I had to do one when I was very gravely ill when pregnant with my oldest daughter. Its now 6 years out of date. I should really redo it (and you too jinkzd <pointed look>). Thanks for the reminder. this is an often overlooked but very valuable thing to do. Another thing to consider talking about with your family is your wishes should you be in a horrible accident (heroic measures, life support, etc etc etc) and your preference for how you are laid to rest.
An important part of this is people who are unmarried but share a domicile. Should something happen to the other, communal property doesn't necessarily go to the gf/bf, it goes to the family.