The folks over at SamMobile have managed to get their hands on an Android 4.2.1 Jelly Bean based firmware for the Galaxy S3. Samsung is still testing Android 4.2.1 on the Galaxy S3, and the leaked firmware is nowhere near final even though it is relatively bug-free.
The Android 4.1.2 update brought with it a lot of new features to the Galaxy S3. However, it looks like the Android 4.2.1 update will only bring minor new features including voice actions for controlling the Camera, Radio, Music playback and call.
While Samsung has included all the features that Google introduced in Android 4.2.1 including Quick Settings, Lock screen widgets and Daydreams. Notably absent is the Photosphere feature from the Camera app. However, it may be possible that Samsung will add this feature in the final version of the firmware. Samsung has slightly changed the lock screen ripple effect, along with slightly tweaking the toggles in the notification bar to accommodate Quick Settings. How useful the voice commands feature that Samsung will introduce in the final build of the firmware only remains to be seen.
SamMobile states that Samsung will be releasing the Android 4.2 update for the Galaxy S3 only after it unveils the Galaxy S4. Samsung is expected to unveil the Galaxy S4 at an event to be held on March 15th.