I get mora than 24 hours of battery on my Lumia 1520.1 WP 8.1. No BS, i play and watch videos and play music and use whatsapp. I also get toasts from Facebook and email.
Proof:
http://imgur.com/qoqSuY6&ofZlP2d
In about to leave work and have 53% battery left, 14 hours to go.