Whatsapp is a little gem on a company which no one talk about. It's hard to get inside information about the company on the internet, and maybe that's the geniuses of co-founders. They don;t talk so much about the company and instead focus on building a quality product.<p>On a comparative note, the product is actually not so good(maybe because of the sacle they are operating on). They have problems with their backend, few of the front end apps are not so good eg blackberry but increasing number of users is an achievement which is the scary part for facebook.
I am in Pakistan. This is a place where most people don't use credit cards on the internet, sms packages are dirt cheap like $1/month for unlimited texting, and we have no 3G internet(only EDGE) but still majority of the people use whatsapp. Almost everybody i know uses whatsapp and they have been using for more than a year. One you get hooked on whatsapp people are forced to pay.<p>Whatsapp has a lot of potential to challenge facebook to a certain extend. They introduced profile pictures a while back, and the 'last seen at' update is like a gold. Ramp up whatsapp with a few BBM like features, extensive photo sharing, and geo location features(anonymously chat with people near you) and they can be a worthwhile competitor.