Puppy mill dogs as pets?

Do any of you have knowledge of problems making pets out of puppy mill dogs? I saw a dog at the Pet Rescue we have gotten both dogs and cats from. The worker told me she was from a puppy mill. This little dog, about 7 years old, predicted, so sad, what kind of problems would I have if I picked her to go home with me? I know she was kept in a crate all her life, which means she is not house broken. How difficult would that be to break the habit? Any thing else? What would you advise me to do? Thanks for your input. Jen