The Gran Hotel Hispano has small rooms, "cozy" at best. The same goes for the bathrooms, which fit one and whose showers are not separated from the rest of the bathroom--with the result that the floor will be wet for at least an hour each time you shower. On the up side, the water is hot and plentiful, and the rooms are kept warm in the winter.
The best thing about the hotel is its price, particularly given its location. It is on Avenida de Mayo, right next to the Gran Café Tortoni and its fabulous chocolate con churros. Calle Florida, Avenida Corrientes, the theater district and the presidential palace are all within walking distance, as is San Telmo (15 minutes or so away).
The breakfast offered is decidedly unimpressive: toasted sandwich bread or "media lunas" with coffee or juice drink (ask whether it's made with local water). You're best off, if you can afford to, to eat at Tortoni next door, or somewhere else.
The beds are made every day, and the cleaning and serving staff are friendly enough, although obviously it helps to know Spanish. The front desk attendants are professional, and the hotel management are efficient, albeit occasionally a bit impatient.
Basically, what you get is a good, solid hotel in an absolutely central location at an incredible price, at least by American standards. Reserve way in advance if you are coming in during a peak season. Keep your expectations low. As two star hotels go, it is excellent.
One thing about the location: although it is central, Avenida de Mayo is practically empty at night. My bet is that there are other areas of the city that are a bit more lively at night. But since the hotel is on the avenue that is home to the presidential palace, you won't feel all that unsafe.