I was using this yesterday. I dumped all postmortems for an aspect of our infrastructure into a notebook and could then ask it to pull out common themes. It was remarkably effective. I also generated one of these "audio overviews" (aka podcasts) and it was great.
There was a vast improvement in quality from giving it a prompt when generating the overview. The generic un-prompted overview was for entirely the wrong audience, in our case users of our infrastructure rather than the developers. When instructing it to generate an overview for the SRE team and what they should focus on it was far better.
Was it useful for our in-depth analysis, no. Would I listen to one based on the last 100 postmortems for a new team I joined, absolutely. As an overview it was ideal, pulling out common themes from a lot of data and getting some of the vibe right too.