When used to stir hot food, a wooden spoon stays cool to the touch and won't scratch the pan. When mixing ingredients, the paddle shape of a wooden spoon blends better than a metal or plastic spoon.
Some people are concerned that wooden spoons may be unsanitary, but this is not the case. Wood is naturally antibacterial, and when manufactured, wooden utensils are treated with mineral oils to create a surface where bacteria won't easily grow.
Wooden spoons shouldn't be put in a dishwasher or washed in extremely hot water because they dry out and crack. They can occasionally be rubbed with mineral oil to keep them smooth and prevent cracking.