Make sure you get your ferret from a reputable ferret breeder. Not from a pet store.
If ferrets aren't handled a lot as they grow up, and if they aren't taught not to bite at an early age, they will indeed bite. Hard.
My grandma has two ferrets that they got from a breeder, a brother and sister. They're the sweetest things ever. The girl is shy, and the boy will lick you. He'll sometimes play-bite, but he does it extremely softly so it doesn't hurt.
On the opposite end of the spectrum, my sister used to have a ferret. We got him from a pet store. And he would not only bite you, but he would bite you in the softest spots he could find. Let him crawl up your arm? No way, if you didn't want him to latch down nice and hard on the soft spot where your arm bends.