It works great with my kids sometimes. Asking a series of questions about some kid-level science topic for instance. They get to direct it to exactly what they want to know, and you can see they are more actively engaged than watching some youtube video or whatever.

I'm sure it helps that it's not getting outside of well-established facts, and is asking for facts and not novel design tasks.

I'm not sure but it also seems to adopt a more intimate tone of voice as they get deeper into a topic, very cozy. The voice itself is tuned to the conversational context. It probably infers that this is kid stuff too.

Or it stops talking mid-sentence because you cleared your throat or someone else in the room is watching TV and other people are speaking.