These are the chatbots that don't work. They're simple scripts that can not handle new information, and fail to recognize requests that fall out of a very narrow path of wording.
It's good at some tasks, but it's ranging from inferior to inadequate for many others. The biggest drawback is its opaque affordances. It's not immediately apparent what is the range of things I'm able to ask a chatbot about, even if its language processing is advanced. This is a problem with humans as well. Like if you ask me which questions I'm able to answer, I won't be able to provide an answer.
Overall I feel like natural language interfaces is like 3d cinema. It's a novelty more than bringing much actual value.