After six months of teaching I was sick of it, but managed to finish out the year. Not because I didn't enjoy teaching, but because I was overworked, underpaid, and generally mistreated by several institutes. I got fired from one institute when I got the flu, for example. You are en negro, which means you pretty much have no rights other than calling AFIP. Never, ever forget that.
I started in February 2010, when many institutes were still trying to pay 25 pesos per hour, 35 if you were very very lucky. Teaching is how I learned that honesty and loyalty are qualities that will only do you financial harm as an employee. Also, many institutes are in the red and so will often pay you weeks late. That or they'll claim your money is ready, then you go, only to wait 45 minutes to told that in fact it is not ready; come back next week. Then the next. I worked for five different institutes that were all on my TEFL program's "approved" list, god knows why. If I had to do it again, I would try to poach students from the institutes immediately and teach them privately--they save money, I make more, everybody wins. But I have a friend who has tried to go all private, and it's hard because of frequent cancellations, disappearing students, etc. She works six full days a week and I don't get to see her much, but I say good for her. She is determined to stay here in BA and is doing what she can.
What I do miss is being exposed to every type of Argentine, from the entry level guy at Accenture who has a two-hour commute from the south every morning, to the president of the board of the advertising company who owns a huge house in Olivos and vacations in Europe and Patagonia every year.