Sadly, no one has a "real" smartphone in Argentina due to president Cristina Kirchner's import restrictions, not due to lack of income.
I live in Uruguay, right across the border, same median income basically, and a lot of people have smartphones: there's a chinese smartphone with Android made by ZTE for Movistar that is given away for free, and Samsung Galaxy Mini is also free with 15 dollar contracts. Huawei also has a very cheap smartphone.
I have a Samsung Galaxy Ace as well, which is the most popular smartphone as it is among the cheapest handed out by the state telephone company (Antel).
I can second the fact that Facebook is king here, I have 3 teenager cousins and 2 nephews about dysoco's age, and they use Facebook a lot. Twitter only to follow Justin Bieber and One Direction as well :) .