UI

- Transitions more polished!

- New 'choose default window'.

- Blue bar at bottom of notification pulldown is grey when not depressed. Blue when held.

- The menu buttons glow gray

- New "Complete when using" window... (ie when you install a new home launcher)

- The ability to block apps from using notifications

- Date and time in the notification bar when pulled down

- Notification for the screenshot shows a preview

- When you add a word to the dictionary it no longer takes you to a different screen. A popup appears instead

- When you add a word to the dictionary it no longer takes you to a different screen. A popup appears instead

- Pulling down the notification slowly dims the background

- You can store contact photos that are as large as 720 x 720 !

- Data Usage Graph is now linear, like in CM9

- When keyboard is active, the back button turns into a downward arrow

- There is an other lockscreen animation and you can access google now from lockscreen

- New Wallpapers

- New Search-Bar

- New Radio and Bootloader (For GSM phones)

- New Boot-Animation

- Expandable Notifications with a new notification bar

- New animations in gallery app

- New share action and intent picker pop out (big icons instead of a list)

- Default font seems to be a little thinner than ICS Roboto in some places

- In Settings -> Apps, it now allows you swipe between tabs.

- You can hold down the notification bar on the top of the screen to see the time and date

- When you click on a link or a file that has multiple apps that can open it and you get the new screen to choose which one to open with, you can long press on the apps to go directly to the app info screen



Performance

- App Updates: When a developer publishes an app update, Google Play now only delivers the changes bits of the application rather then the entire APK. This makes app updates much lighter and easier on your network data. On average, a smart app update is about 1/3 the size of the full APK update.



Apps

- Messaging now has a native widget

- New Google Music widget, Google Music has a slightly different UI too.

- New calendar notification window

- When using google music and a notification comes on it will now lower the volume rather than mute the song.

- New Youtube App (When you pause a video by either yourself or an incoming text/call, it resumes the video and plays where you left off. It won't start over now!)

- New Google Maps app

- Optimized Camera app

- No root restriction on google play movies

-



Tricks/Tips

- Launch Google Voice Search from lock screen by sliding up or press and hold on any button in the navbar

- Widgets/Apps now move out of the way to allow for easier rearrangement

- If you slide up on any of the menu buttons, it shows a Google icon that takes you to Google Now/Google Search

- While in the camera app you can swipe to go to the gallery, then swipe back to get to the camera

- When looking at recent photos and you pinch it, you can then swipe left and right. If you swipe the photo up it deletes it which makes it easy to delete several photos at once if you want.

- New throwaway action (flick the widget/app)

- You can long press a notification and get into the app info screen

- Keyboard shortcuts (example: brb expands to "be right back").

- To take a screenshot hold Power/Volume Down

- For HD contacts, you CANNOT use GMAIL/GOOGLE VOICE to set the picture. You have to do it within the phone using the peoples/contact app!



Settings

- Ability to block apps from reading SD content.

- More options for forcing HW acceleration & GPU rendering

- Hotword Detection: launch voice search when you say "Google" (when you are running google now)

- There's a new option in Face Unlock that will require you to blink before it unlocks the phone. That can take care of the issue of a phone getting unlocked with a picture

- Wi-Fi Direct has now an option menu:

- WPS-Pin is now supported:

- The account-settings are now a seperated category in the settings

- Developer options have been rearranged and new ones have been added

- In contacts, there is a "Auto-sync app data"

- SAFE BOOT: long press on "Power off" (in the menu that shows up when you long press power button) to get into this mode. Only system apps will be loaded (should come in handy when dealing with rogue apps)

- Android Beam: Android Beam hands over from NFC to Bluetooth, making it easier to transfer and manage files between devices

- In contacts, you can auto-sync the app data



Official Change log: http://www.android.com/about/jelly-bean/





