Ironically, in Canada, data costs an arm and a leg while unlimited text messaging is the norm lol. I rarely use WhatsApp but it's a good alternative in low signal zones (but good WiFi coverage) or to send pictures to friends.
I used WhatsApp on Android phone. Sometimes it takes over a day before the message is received on the other end. It lagged so bad that I had to uninstall it. Using google messenger from the browser is faster.