Lenovo has started rolling out Android Marshmallow OTA update for the K3 Note in India. The update weighs in at about 1650 MB, which is quite large even for a major release.
The update changelog doesn't say much, apart from the fact that you are getting Android 6.0 Marshmallow. At present we haven't got the update on our unit, and it seems like a gradual rollout. If you haven't got the OTA update notification, check in Settings -> About phone.
From what is apparent, the new build will bring better battery life, performance, some UI tweaks to Lenovo's Vibe UI skin and possibly some camera improvements as well.
So tell us your experience with the Marshmallow update on the K3 Note in the comments section.