JoeBlow said:
The amount of slang used in Buenos Aires is no greater than that used in any other dialect of Spanish. Every regional dialect of Spanish and English has lots of words that outsiders won't understand the first day they're in their new city/town.
I am not referring to slang. I am talking about everyday things that if you learn spanish here you will not be well understood in other countries. Argentina and especially not Buenos Aires capital federal are good places to get a baseline use of spanish or "castellano" as they say here.
For example go to a verdulería in any other country in latinoamerica or the carribean (except maybe chile where they are used to hearing this strange use of español) and ask for ananá, damasco, frutilla, pomelo, frutos del bosque, chauchas, and nobody will know what you are talking about.
(The correct words are piña, albaricoque, fresa, toronja, frambuesas, and judías verdes)
Go to a real estate agency in any other country in latinoamerica or the carribean and ask for 2 ambientes living con placard, y amoblado con sommier and see if they have any idea what you mean.
The correct way to request this would be departamento con 1 dormitorio, sala con armario y amueblado con colchón y marco de resortes.
These are everyday things that people ask for and do and if you get your baseline spanish from here you will only have to re-learn it somewhere else. If that doesn't matter to you then go for it! There are lots of things that are worth learining here, like tango, how to make different repulgues for different kinds of empanadas, authentic parrilla argentina, however language is not one of their finer points.