BA definitely has that 'big city,' feel. Word is that it's the Paris of South A., but as a North American, it felt very 'New York' to me. It is definitely a large, metropolitan city with a lot to offer. One, nice to me, thing is that due to the large diversity of the cities' inhabitants it's not hard to blend in. Do the typically written about things (La Boca, MALBA, Recoleta Cemetery, San Telmo) but also, less written about, the Ateneo bookstore which used to be a theater and is in Palermo.
Insider Tip:Bring American dollar, go to Florida street and exchange at a rate of ~10-11 pesos per dollar (bring large bills, 50 and 100, for the top rates). If you're staying for a week or longer and don't want to walk all the time/pay for taxis, get a Sube pass. They can be hard to find, you can recharge them everywhere, so ask around from the beginning and you can ride the subway and the bus (you can still ride either but will about 2x and can only use coins for the bus). But it's a very walkable city.