I just switched carriers from Verizon to AT&T and thought it would be a good opportunity to branch out from the iPhone I normally carry. I had tried an HTC 8X last year and battery life was my main complaint. Needless to say, it was also a concern when considering the Nokia 925.
Luckily, I have been pleasantly satisfied with the battery life. As people have said before, the first couple of days, battery life was pretty bad (almost returned to a Moto X - tried that for a week or so before the Lumia). But I stuck it out with the 925 and now am super glad I did. I leave WiFi, location, and Bluetooth on; on LTE most of the day. I have NFC, glance, and display "double tap" turned off. While they were nice at first, I found that I didn't really use them on a regular basis. For accounts, I have Facebook, Twitter, and 3 email accounts synced. Overall, with 30 min GPS to work and 30 mins home, regular texting and browsing Facebook / Internet, I can make it a full day on a charge. However, I do carry a charging cable in the car just in case.
Is it the best battery life I have had? No. But I feel that it is satisfactory for how i use it and I know I could get a lot longer life if I would just leave it alone!
Screen and GPS are big battery killers. Not familiar with Whatsapp, so not sure how it would be affected.