What do you look for in a prosthetic hand?

Arglebarf writes: A family member is recovering from a serious illness and, unfortunately, the medication that saved her life will probably cost her hands and feet. She is an artist by trade, so this is a pretty big deal. Replacement prostheses might restore a degree of independence, as well as enabling her to continue with her creative passions. Do any slashdotters have any experience with replacement hands? What features do you look for? Do any models allow you tweak the software for fine tuning? Beyond the day to day uses, she will want something that can hold small objects precisely (i.e. a paintbrush).