I did like the fact that the AR Ruler app - Measure is now a part of the OS. When ARKit got announced last year - I wasn't super pumped about it as Apple was but there are some cool apps that utilize AR. The ruler apps were one of the first to hit the market last year and I guess Apple just took them over now LOL.
Filmr is another cool free app that utilizes AR. It lets you make fun videos with AR objects in them.