I am from the United States but have been living in Mexico for almost nine years. I use WhatsApp to text with and call my sister in the U.S., friends in Nicaragua, Chile, Argentina, and Uruguay, as well as with a few businesses. I have Whats for the web, and it's on my phone. I also participate in family groups and lead an English Mastery group. I have literally never had a problem with WhatsApp. I can recall only one outage in the 10 years that I've been a WhatsApp user. The messaging app is fantastic, as is the quality of the audio during calls. Possibly, some people expect their personal WhatsApp to resemble a Facebook timeline, but that's neither what it is not what it aspires to be. As a messaging app it's near perfect.
