I have been using whatsapp since 5 years. For me it is the best commucating app with friends. You can easily share pictures, vedios, musics, and the best part whatsapp calling. Its free and very easy. Even works on slow network I mean 2g network very well. Where other communicating app does not work properly on 2g network. The calls made using whatsapp is very clear and smoth. Very fast sharing of photos and vedios. And downloading of pictures and vedios are also very fast.The best part I like, after registering a number in one device, if you change the sim your account remained on the device. If you want to use your old number , you can continue.Try whatsapp atleast once you will gone love it.