During the weekend an Android 4.3 update for the Samsung N7100 Galaxy Note II (the non-LTE version) leaked, but it wasn’t compatible with the N7105 (the LTE version). That doesn’t matter anymore as Samsung is rolling out the official update for both.
The update is reportedly more stable than the problematic 4.3 update for the Galaxy S III, which along with the Note II launched with Android 4.1.2 last year. Samsung decided to skip 4.2 and go straight to 4.3.
Anyway, the update is rolling out in stages, so don't worry if you don't get it immediately.
You can use Samsung Kies on the PC or just check for updates on the Galaxy Note II itself through the About section of the settings menu.
Here's a changelog of the new features, which also includes support for the Galaxy Gear smartwatch.