New interface elements and features borrowed from the Note 3 included
Samsung has stated that it's on track to have a Galaxy Gear-supporting update ready for the Galaxy Note 2 by year's end, and it looks based on a leak today that that update will also be to Android 4.3. A full build of test firmware for the international (GT-N7100) variant of the Galaxy Note 2 has leaked, giving us a look at a mid-cycle but relatively complete build.
The firmware has a new interface that draws from what's seen on the Galaxy S4 and Note 3, and includes new features like Samsung Knox and Samsung Wallet. It is said that Samsung is pretty rapidly working on the software and new builds are coming out every two days, so things are likely to change some between now and the official release.
The test firmware (build N7100XXUEMJ5) is available to be flashed on your own Note 2 provided you have the right model, and the folks at SamMobile claim that this will not increase your flash counter. If you're willing and able to flash the test build yourself, keep in mind the regular caveats of the likelihood that there are bugs and issues in the build.