This is apparently out today, Friday 17th October 2014. This seems very much about making android work better on lots of different devices. These are the headline features:
Material Design
- “A bold, colourful, and responsive UI design for consistent, intuitive experiences”..
- More vivid typography and edge to edge imagery.
Notifications
- View and respond to messages directly from your lock screen.
- Priority mode so only certain people and notifications get through to a timed schedule.
- Better control over app generated notifications.
Battery
- A battery saver feature which extends device use by up to 90 mins.
- Estimated time to fully charge and time before charging is required.
Security
- Encryption auto-on.
- Better protection of O/S against malware / vulnerable apps.
- Smart lock by pairing it to another Android device (watch / car, etc).
Device Sharing
- Multiple users for phones – apparently you can access your contact / messages from someone else’s phone.
- Guest users for phones and tablets.
- You define what another user can access on your phone.
Quick settings
- Handy controls for flashlight, hotspot screen rotation and screen casting.
- Easier toggles for wifi, Bluetooth and location.
- Manually adjust brightness then adaptive kicks when lighting changes.
Connectivity
- VoIP / video chat should work without interruption when going from wifi to mobile network.
- Better network selection logic
- More power efficient scanning for Bluetooth.
- New BLE peripheral mode.
Experience
- Faster experience due to ART, the new Android runtime.
- Claims of up to 4x performance improvements
- Smoother UI
- Background apps get compacted to save memory.
- Better 64bit support
Media
- Lower latency audio for better music / voice comms
- Multi channel audio stream mixing
- USB audio support for microphones / speakers, amps, etc.
- OpenGL ES3.1 for better graphics.
- Full resolution capture at around 30fps
- Support for raw formats like YUV and Bayer Raw
- Control camera sensor / lens and flash per frame
- Capture meta data like noise models and optical info
- HEVC allows for UHD 4k video playback + tunnelled video for playback on Android TV
OK Google
Talk to google to get answers has been improved
Misc
- Android TV has been improved in various ways
- Better support for people with poor vision / colour blindness.
- 15 new languages
- Easier device set up and app migration to new devices.
- ‘Tap & Pay’ manage multiple payment apps by quickly switching between them?
Better printing support
- New display for batter, Bluetooth, data usage, wifi settings and new search function in settings.
- Android Beam improved.
- Where supported by hardware, device will wake up when you pick it up or tap screen twice.
- Improved hardware keyboard accessory support.