OK I don't get what does Ice Cream Sandwich have?
• Option to use virtual buttons in the UI, instead of taking up capacitive touch buttons
• Widgets are in a new tab, listed in a similar list to apps
• Folders are much easier to create, with a drag-and-drop style similar to iOS
• A customizable launcher
• New phone app with visual voicemail functionality that lets you speed up or slow down voicemail messages
• Pinch-to-zoom functionality in the calendar
• Gmail has offline search, a two-line preview, and new action bar at the bottom
• Swipe left or right to switch between Gmail conversations
• Integrated screenshot capture by holding power and volume down buttons
• Improved error correction on the keyboard
• Ability to access apps directly from lock screen (similar to HTC Sense 3.x)
• Improved copy and paste
• Better voice integration
• Face Unlock, a facial recognition service
• New tabbed web browser, allowing up to 16 tabs
• Browser now automatically syncs your Chrome bookmarks
• Modern "Roboto" font
• Data Usage section in settings lets you set warnings when you reach a certain amount of use and disabling data when you go over your limit
• Ability to kill off apps that are using data in the background
• Camera app: zero shutter lag, time lapse settings, zoom while recording
• Built-in photo editor
• New gallery layout, organized by location and person
• Refreshed people app with social network integration, status updates and hi-res images
• Android Beam, a NFC feature that lets you exchange websites, contact info, directions, YouTube, etc.
• Don't like some of those preloaded carrier apps? Disable them.