Microsoft had promised that by the end of this month, February, all Lumia Windows Phone devices running Windows Phone 8.1 (Cyan) will receive the much awaited Lumia Denim update. The Lumia Denim update brings a bunch of exciting new features especially in the Camera space. Fo a full list of features visit here.
If you own a Lumia 820/920/925/1020 or a Lumia 1520 , head to phone update under settings, and check for updates. Earlier, the Lumia 620 and Lumia 720 received the update while as the Lumia 520 was one of the first devices to pick up the update in India.
Source: Microsoft