Contacts in Dialer: The option to add a contact when entering a phone number has been altered slightly and is now executed by tapping the + sign next to the phone number. Previously, there was a line that said “Add to Contacts.”
Messages Scrolling: When scrolling through the Messages app in beta 4, it seems there is slightly more “bounce.” This is in line with previous changes to Control Center, which introduced a bounce animation.
Siri: In the U.K., there is a new Siri voice on the iPad.
Slide to Unlock/Power Off: Most notably, the Slide to Unlock bar at the bottom of the phone is now more prominent, with a brighter, slower animation. The same brighter animation can be seen in the Slide to Power off bar when turning off the phone.