The final version of OxygenOS 3.0.2 does not have many differences from the two beta versions of the OS launched earlier. It is just fine-tuned to make it more in line with the OnePlus 2 and accompanied apps. Note that the update will clear your stored fingerprints. You will need to re-enroll the fingerprint again before use.
Below are the some of the highlights of OxygenOS 3.0.2 update for OnePlus 2 If you have not received the OxygenOS 3.0.2 update notification on your OnePlus 2, check the availability of the new software by going to Settings > About phone > System updates > Check For Update. If update is found let it download and install (source)