It used to be useful...
I liked Timeline a lot but have noticed features and usability eroding. Used to be able to click on a location and see all the visits you had there, which was very helpful when recommending bars/restaurants.
I made sure data was set to never delete and enabled the back up option when accepting my fate to have the info stored on my phone. I have noticed, since then, that the quality of information on New Timeline is awful. The logic it seems to use when you update missing / incomplete data is bonkers. I keep submitting feedback but I know it just gets binned. I suspect I'm going to just end up turning the feature off if improvements can't be made.