WhatsApp is available in every phone till now , same as that of hike but there is much awareness for WhatsApp as compare to hike. WhatsApp is updating it's app continuously and you can send any notification ie document , audio , easily .
It also took years for people to get aware of WhatsApp but now people know very well about the app and how to use app is easy.
You can open app anytime ,d just need to click a photoeasily can send it to yours friends. It has emoji options and also have a back up facility. it can be install easliy on phone.,