A small one: beta 3 fixes the home view on phones when you have quick actions set up. The greeting, the notification line and the pills were pushed up under the top bar, with an empty gap above the cards (#169, thanks hiroian for the report and the screenshot). Rooms were never affected.
Everything else is as in beta 2: edit mode, the card picker, the new card settings, conditions, the template library and the bottom bar. If you're new to the betas, see the beta 2 notes for the full story and how to switch the pre-release switch on in HACS.
As always: if something looks off, tell me in Discussions or open an issue.