as a professor i'm tentatively pleased. it's hard to shake out the edge cases for anything like this so it may break down or cause annoying problems, who knows.
but even with this feature in this very early state, it seems quite useful. i dropped in some slides from a class and pretended to be a student, and it handled questions reasonably. Right now it seems I will be happy for my students to use this.
taking a wider perspective, I think it is a good sign that OpenAI is culturally capable of making a high-friction product that challenges and frustrates, yet benefits, the user. hopefully this can help with the broader problem of sycophancy.