People like a degree of anthropomorphism in, well, anything. But when designing things with personality, keep in mind that there's, what I call, a valley of creepiness which happens when you add too much realism. E.g. it's probably okay to have a coffee-machine that kind of looks like an animal, but it's not okay to have that coffee-machine defecate perfectly realistic pieces of shit on your carpet.

Universal Principles of Design calls it the uncanny valley: http://books.google.com/books?id=zXAx9_Y8GiEC&lpg=PA243&...