The latest WhatsApp Beta version brings full compatibility with Windows Phone 8.1. The version number for the latest WhatsApp Beta for Windows Phone is said to be 2.11.582.
Battery consumption is greatly improved as compared to the previous versions. There are some improvements in settings on the bottom of the chat too. It also brings ability to crop images for setting in the background.
We have earlier seen some screenshots of a WhatsApp version claimed to be coming soon as the release build.