The straight-forward answer is yes. UBER is indeed available in Buenos Aires although there is much controversy over it, as there has been around the world.
In Buenos Aires, the company operates illegally providing the service to anyone who downloads the app. So, regardless the transgression, you can still take the ride and pay for it with your foreign credit card or in ARG pesos cash. Nothing bad will happen.
You may have read about some violent episodes in which taxi drivers physically threaten UBER drivers and damage their cars claiming that this international company brings forth unfair competition. Nevertheless, these very unusual situations are no deterrent for the thousands of locals and tourist who still choose UBER as the cheapest, safest and most reliable way of moving around.
Since the fares here are very low in comparison to those of other big cities, we do recommend you take UBER Comfort because the cars are much nicer and you will be more comfortable. Note that some drivers may ask you to sit on the front seat to avoid any minor chance of trouble.
If after reading this article you still feel uneasy about using UBER’s services, you can download CABIFY which works just as well as UBER. You will find it a bit more expensive, but it is 100% legal.