[anonu]

I think there's more than 1.3 billion users on WhatsApp - its massive - I am personally checking it constantly (> once an hour)

It's certainly a more popular app outside of the USA. They initially gained traction because they were willing to make apps for things other than iphones and androids - which gave them a huge following in the developing world where people may still use 10+ year old candy bars.

[ohmicmann]

This is so true. Where I live most of people started using Whatsapp on old Nokia phones running SymbianOS. It was one of the few decent apps available.