I like this concept of Web Whats App because many time we are doing some work on internet on Laptop and Desktop so its very difficult to concentrate on Laptop and mobile so its better we use 2 tabs 1 is our browsing tab and 2nd is web.whats app so we never need to use phone for checking whats app message. You just you your keyboard ALT+TAB key so you can easy to navigate your tabs so its better way to chat with friends and do your work at the same time.
The security is this application you only one time login in only one system. You just need to open web.whatsapp.com and you get QR Code then open your Whats app and click on menu key and click on Web Whats app . Scan this QR Code and Done. The security is this application is you can see your web whats app is log in or not on system and only one click in phone you see option log out and your web.whatsapp is log out from all system there you log in previously.
It is very user friendly and just like a tablet view of whats app messenger in this page. its one more good option you see that is you see your phone battery is low or full. Easy to load any time even slower networkw.