Our first experience of Argentina was an immigration official looking at my parents' US passports, noticing their birthplace in Russia, and asking "do you happen to have a Russian passport as well? If you do I won't have to charge you the entrance fee."
They didn't, and paid. I used my Finnish passport, and didn't have to pay. When it was time to fly back, the airline clerk instructed me to show both passports to her, the Finnish one to the Argentina border control, and the US passport to the US border control. (Incidentally, I passed the US border control in Miami, for the first time ever, and was absolutely shocked by the Customs and USDA officials addressing me in Spanish. They did switch to English as soon as they noticed my open mouth.)
The combination of high-trust and low-trust features in Argentina is sort of strange. On one hand, locks, bars (not just the drinking establishments) and guards are everywhere. On the other hand, the population, including lone young women, does not seem to be in any way afraid of being out at 4am. On one hand, any bill starting from 50 peso (about 10 euro) up is checked for being counterfeit by its recipient, and even fairly small credit card purchases often require a picture ID. On the other hand, nobody has ever tried to cheat us in a restaurant.
The people are friendly, laid-back, and mostly southern European in appearance. They are also covered with liver spots in a way that I found scary, and to a much higher degree than in Southern Europe, which made me wonder whether Buenos was much sunnier than, say, the south of Spain, or the sunscreen much less popular.
I really loved the way they tried to correct my Spanish, and started thinking that if I lived there for several months I would be fluent. Once I tried to find matches in a supermarket, and having failed in the attempt to find them by myself, asked an employee for cerillas. He led me where the damn things were, pointed at them, and said in Spanish in a schoolteacher tone: "Fosforos. Only Bolivians say cerillas."
Argentinians seem to love demonstrations, dogs and traveling. We'd seen at least 10 demonstrations in about 8 days in Buenos Aires, mostly on various political topics: they supported some party or other, demonstrated against paying of the national debt, in favor of recapturing the Falkland islands "because our brothers' blood is priceless!" (somebody should explain them the concept of sunk costs), and against drugs. Every self-respecting demonstration had drums, and people who beat them with a big stick and a great enthusiasm, and demonstrations seemed to compete among themselves in how much noise they could create. The only exception was a rather sinister-looking demonstration of people in Che Guevara t-shirts with evil-looking faces, who had very big sticks and no drums at all.
There is a great number of dogs, who are just as laid-back as humans. The city was full of people walking dogs, people walking as many as 10 dogs at a time, and a great number of dogs without any visible people present, who nevertheless did not seem to be strays. Picking up the dog shit from the streets is not common, and one should exercise due caution while walking.
The national parks were full of tourists, most of whom were from Argentina. There was quite a lot of people from the other South American countries, too. The parks usually have different prices for Argentinians, people from the local province, people from the local town, people from Mercosur (Argentina, Brazil, Paraguay, Uruguay) and all others.
Another interesting feature of the national parks was the languages: posted notices tended to be in Spanish, English, Portuguese and Hebrew.