Using beta builds of apps can sometimes not be as rewarding an experience as you'd hope but sometimes it might be worth its bugs. The latest update for WhatsApp beta brings with it a similar Quick Reply option to what Google Plans to do with Android N. Although, it is a bit more like what Line and Facebook Messenger does with a small window showing up. If you want to answer a message. You hit the Reply button and a pop-up window will let you either type in your answer or use the speech input to dictate your response. If you click on the View button, though, that will take you to the thread within the app.
Aside from introducing Quick Reply, WhatsApp has fixed its chat and contact selection to make it similar with how you do selections within Gmail. When you tap on a profile icon or chat group, you can tap more and that will start the multiple item selection process, which lets you select both single and group chats together. The options that will appear after this will vary depending on the type of content you selected. The app also brings with its solid color backgrounds for those who prefer a cleaner background over the somewhat busy WhatsApp wallpapers.
Source: Cult of Android