In China we are all addicted to WeChat (weixin in Chinese). We use it a lot, for chat groups, to record and send pictures and short videos, for (free) video calls, all like a Twitter/Facebook/WhatsApp/Skype combined, to transfer and receive money, to look for people, to send your location, to order a taxi, the list is endless.
So in China, it is enormously popular with over 600 million users

But entering the international market is still far away and for a host of reasons:

• China spies on all communications within WeChat and censors whatever is does not like and cancels subscriber if they “are not behaving”; foreigners (especially abroad) don’t want to to spied upon and censored;
• Some of the advanced functions such as “Official Accounts” (I have one) have interfaces in Chinese only;
• To join larger groups, transfer money and other functions you basically need a Chinese ID and a Chinese bank card, it is very difficult to solve that wall as a foreigner;
• It seems servers have become very slow to handle traffic such as receiving pictures if the sender is not located within China.

As long as those concerns are not addressed (and unlikely to be!), other competing app will be stronger in other countries. Pity.