Even though this is a relatively closed thread, I thought I would share my advice... Read bottom paragraph to skip my story and just read advice...
I feel like I know the city better than most people having lived in Buenos Aires, and surrounding areas for several years. I always thought of Retiro as a safe place, lots of people, lots of tourist, a nice park, nice train station, nice hotels... etc etc However I think I was a little naive in my assessment, and I have a new opinion of Retiro.
Like several others here, the only place I have been truly "robbed" has been in Retiro. Once in the day, and once late at night coming home from Gran Bourg. Both times with my Argentine girlfriend, who to this day, still complains to me about taking her to Retiro, and I'll explain.
The time we got robbed during the day we were coming back from outside of Buenos Aires, and took the train into Retiro. When you get out of Retiro you have three options, go right, middle or left. Right takes you past all the entrances to the other train stations, past all the vendors, and hoards of people. Middle takes you across the park past the big clock tower towards the Sheraton, and left takes you past all the bus stops and then in front of the Sheraton. This was during the day so I thought it would be better to cross the park next to the little clock tower. As soon as we got near the clock tower several men approached us and opened their jackets to show some type of gun. Now I just kept on walking faster, but my girlfriend moved to my other side and we walked faster. We were lucky.
The time at night we decided to go right. At this time, at night, there were very few people and we were actually a little more relaxed because we didn't see anybody. We started walking, we crossed the big street, Libertador, and started walking up the street (Calle Belgrano) next to the park. i was joking with my girlfriend that if anybody robbed us, I would tell them take her and then I would run. As soon as I said that, someone came from behind us and opened his sleeve which showed a big piece of cut glass and asked us for money. We kept walking and told him we didn't have any money. Again very lucky to escape. So we didn't technically get robbed but we were threatened with violence and luckily escaped both times.
So in summary, if you didn't read anything I just wrote, I would say avoid Retiro at all cost, avoid calle florida and all that area. If you have to be there at night I would recommend a taxi, or take your chance going "right" along the street,crossing Libertador and up Belgrano, but walk fast, and look for other people (no shady looking people) to walk with
We got lucky but I wouldn't recommend being around Retiro at night, like others have said, please take a taxi.
The problem with Retiro is Villa 1.