This is a complete list of all the upgrades that have been made to the Galaxy S3 over the S2, Software and Hardware (if i have missed something let me know)
Galaxy S3
Hardware
64GB Microsd exFAT Support
Apt-X Codec Support ( Improved lossless Bluetooth audio)
Active noise cancellation with dedicated mic
Backside illuminated sensor (takes better photos at night)
Battery life Improved (2100 mAh)
Barometer sensor
Bluetooth v4.0 with A2DP, EDR
Bigger Screen (Better web browsing, Improved Multimedia experience with a larger screen)
Burst Shots (up to 20 pics)
Eye tracking technology (Smart Stay -no more going to sleep while reading a webpage)
Faster Mali-400 GPU
Faster Shutter speed
Front Camera HD video
GLONASS support
Gorilla Glass 2
HD screen
Internal Storage Improved 64GB
LED indicator
Louder Speakers (2x 2W Speaker)
NFC support (S beam- can transfer files up 300 Mbps)
Quad Core -Exynos 4212 Quad (Benchmarks shows its the fastest Chipset ever and uses less power)
RGB sensor
S Pen support
Slimline back (no more ass sticking out)
Audio Quality Improved (Wolfson DAC )
Thinner Bezel
Wireless Charging Support
Software
50GB Dropbox (free on-line storage)
Allshare cast – Allows you to mirror your screen onto a TV or monitor wirelessly -Need a dongle)
Direct call (don't need to press the "call" button any more)
Improved Social Network integration
Improved Voice Commands ( don't need to press any buttons, very use fall when driving)
Pop up Play (multi task while watching a video)
Smart Alert ( don't need to turn on your phone to see if u have a missed calls or msgs, automatically vibrates when you pick it up to let you know)
Simultaneous HD video and image recording
Galaxy S3
Hardware
64GB Microsd exFAT Support
Apt-X Codec Support ( Improved lossless Bluetooth audio)
Active noise cancellation with dedicated mic
Backside illuminated sensor (takes better photos at night)
Battery life Improved (2100 mAh)
Barometer sensor
Bluetooth v4.0 with A2DP, EDR
Bigger Screen (Better web browsing, Improved Multimedia experience with a larger screen)
Burst Shots (up to 20 pics)
Eye tracking technology (Smart Stay -no more going to sleep while reading a webpage)
Faster Mali-400 GPU
Faster Shutter speed
Front Camera HD video
GLONASS support
Gorilla Glass 2
HD screen
Internal Storage Improved 64GB
LED indicator
Louder Speakers (2x 2W Speaker)
NFC support (S beam- can transfer files up 300 Mbps)
Quad Core -Exynos 4212 Quad (Benchmarks shows its the fastest Chipset ever and uses less power)
RGB sensor
S Pen support
Slimline back (no more ass sticking out)
Audio Quality Improved (Wolfson DAC )
Thinner Bezel
Wireless Charging Support
Software
50GB Dropbox (free on-line storage)
Allshare cast – Allows you to mirror your screen onto a TV or monitor wirelessly -Need a dongle)
Direct call (don't need to press the "call" button any more)
Improved Social Network integration
Improved Voice Commands ( don't need to press any buttons, very use fall when driving)
Pop up Play (multi task while watching a video)
Smart Alert ( don't need to turn on your phone to see if u have a missed calls or msgs, automatically vibrates when you pick it up to let you know)
Simultaneous HD video and image recording