While in Buenos Aires, without knowledge of Spanish language, this mobile app can come handy. I found it when I was browsing app store and searching apps built around Buenos Aires. What made me feel like this taxi cab application can be a good option, is the fact, that it is sponsored by the Argentinian government. They have few more apps available for iPhone as well as for Android. So I felt much safer using this and not knowing Spanish.
The smartphone app is easy to download and you need to fill in few details about yourself after first launch of the app. Then you are ready to get your first taxi. This app also helps you to see the estimated prices before ordering a cab. The interface is very simple even without knowing Spanish and you can order Buenos Aires taxi in few simple steps.
The prices you see are in pesos and you can access/reject the driver if you don't like him for whatever reason. Paying is in cash to the driver in pesos at the end of your journey. The taxi drivers must always switch the taxameter on. The price should be more less what the app shows. The only issue you will face is the internet access and maybe having cash on you. I can see there is also an option for payment cards, in the app, but I haven't tried.
Always verify that the driver who accepted through the app is the one coming for you - car reg number, car type, drivers name. It is like an taxi Uber in Buenos Aires. But you are getting safe licensed drivers, same you would get through a call to an taxi service. The driver can confirm the address with you, so don't be surprised and know at least couple Spanish words to reply back and confirm. And always greet the driver when you enter the car. I safely made around 6 journeys without any issues. One even at 6am. Only one of the 6 drivers could speak English. One more thing. Don't forget that you need internet access to use this app. Before I got my Argentinian number, I had to be at free WiFi location (eg a pub).