I like that this a tool any leader can use, regardless of any other factors. If you're interested in retaining people, being proactive about understanding what their needs and plans are is vital. The book provides some simple pointers that are usable. I haven't fully embraced it - some of the suggestions just seem way too awkward, but overall it's a good idea and an easy read.
While I do think it's very important for managers to use tools like stay interviews, I don't totally agree with the notion that people don't leave over salary as suggested by the author. I appreciate the research on the topic, but what that misses is a bigger picture where our corporate system oppresses people on a large scale - people are very broadly underpaid in so many fields. Companies use books like this against managers - effectively shifting all blame for underpayment.
But that larger point aside, it's still a perfectly useful and valuable tool that any leader should use.