Hey There, I live in Buenos Aires and I can tell you that is a city with a little bit of everything.
The picture that you posted is from particular area or neighbouhood.
You have many different neighbourhoods with different looks.
You have the old-french-european ones , the super modern "Puerto Madero", a typical argentine neighbourhood like "Belgrano" , "Palermo", etc...
Then at night, I highly reccomend you to go to Palermo, that looks like the Soho from NY.
Palermo Soho :
http://www.google.com.ar/search?hl=e...0l0l0l0l0l0ll0
Palermo Hollywood :
http://www.google.com.ar/search?hl=e...1l1067l2-3.1l4
If you stay longer you can also go to ver cool Museums & Art Galleries and also a Soccer Match wich is a nice attraction for non latin people
You can find cool apartments here :
www.roomsinbuenosaires.com
Let me know if you need any help, I will be glad to guide u