I periodically experiment with location history. I currently have it enabled to be able to see my own history and I also record it locally with a third-party app that saves it to my phone. I've compared the location data and looked for patterns or anything at all interesting. I've also thought about building an app to basically give you the same functionality as Google's location history while keeping all the data out of the cloud and in your direct possession. I think it can be useful and interesting to have this data on yourself, I just think Google shouldn't have it.