"Xiaoice is not a polite listener. She answers questions like a 17-year-old girl. When a person pours out his or her heart to her, she is not always predictable. She can become impatient or even lose her temper. This lack of predictability is another key feature of a human-like conversation."
Predictability is a huge part of conversing. I expect a lot of range and flexibility in conversations, but definitely not unpredictability. It seems like an ai (chatbot, rather) behaving unpredictably just covers for it's lack of abilities and tact.
Nonetheless, this is still a very cool project.