The coffee tastes the same to me. The two big differences are:
(1) It takes forever and a day to actually get your cup of coffee! In the time it takes to serve one customer in Buenos Aires, they'll have served 10 customers in NYC or London. Bring a good book to read while you're waiting for the barista to work his "magic"
(2) The prices do not reflect the cost of living or average salaries in Argentina so the same cup of coffee is considerably more expensive relatively speaking