Renting Alejandro's apartment was a great decision, and I would do it again. Great location close to main shopping avenue (Cabildo) and public transportation hubs (bus and subway), building and apartment is very modern with a electric key lock and doorman, and a pool on the terrace with great views of the city. The apartment itself was really nice and cozy with a balcony. The bed was a little awkwardly placed, leaving no room on the end to walk around, but the bed was really comfortable so my girlfriend and I didn't really mind. Lots and lots of closet space, plenty for two people.
All in all I'm really happy with my choice to rent Alejandro's apartment. He was very transparent, and easy to contact, before our trip and also during the trip.