Setup, rebuilt.
You now pick your apps and set your daily limit first. Android's permission screens come after, so you know exactly what you signed up for before anything asks for access.
Also:
• Today's usage now tells you how it compares to your average
• Cleaner, sharper look across the Home stats
• Notifications and battery setup are one step instead of two
• Replay the walkthrough any time from Settings
• Various wording and layout fixe