Comment by grapheneos

Saying it's going to be released later today means to the Alpha channel. GrapheneOS and each of our apps have Alpha, Beta and Stable channels. Every Stable channel release made it through Alpha and Beta channel testing. We don't expect the initial Messaging app release to reach the Stable channel. AOSP Messaging hasn't been actively developed since around Android 5.x and nearly no one is going to be unhappy with the changes.

We're changing very little about the overall layout and structure of the app in this initial phase of the overhaul. Over the past couple months, it was carefully ported to Compose with a lot of code review and added tests. It was a lot of work and is going to look a lot more modern. It's also now possible to greatly improve the user interface in much more substantial ways than making it look modern.