From what we can tell, all that’s really changed is the app’s ability to pull in the device theme color, which is a big part of what Material You is all about. Pretty colors. Other than that, it’s the basic Contacts app that I can’t say I’ve actually ever opened.
I’m running version 126.96.36.1990944461 in case you want to check your own.
Update: As a few people on Twitter have pointed out, maybe I was late to the party? Regardless, it’s there and that’s cool. Have a good weekend, folks!