>>visage+(OP)
I've been mostly using it as what I would call a "medium scope search engine". Instead of searching "$topic" or "$topic site:wikipedia.org", I can pick a few dozen links from different sources (wiki, documentation, tax code, papers, videos), toss it in NotebookLM, submit my search query in the form of a question, and look at the linked source. I see it as an evolution of doing research through library books, Internet search, and Wikipedia. I didn't know I wanted something like this until I used NotebookLM this way. It also seems to handle multiple languages reasonably well.