On iPhone I only see Signifcant Locations; on my phone I only see a list of 3 places (despite 400 records). Compared to Google Timeline it’s much more curtailed function.
Yeah, it's a feature enabled by default outside of the EU (in the EU it asks you if you want to enable it). Makes for some fun stats/recaps, and is useful for tracing back steps (wait, where was that awesome store/restaurant/park/whatever we went to while on a trip to XYZ?) at the expense of Google knowing a lot about you.
I like that it tells me what lane to be in, so it's my main mapping app. Also presumably better privacy than Google Maps.