PROS
Overall: The place was exactly as in the pictures. Clean. Good, central location close to the metro (Sol). Many restaurants nearby, albeit touristy. There was also a convenience store/grocery right across the street. There was also a large window/small balcony which we could open and control the blinds.
Communication: Helios responded quickly when we had queries.
Bed: Good size for two people. There were extra blankets in the closet if we needed it.
Kitchen: The kitchen was well-stocked with a pan, a pot, and dishes and cutlery that we would need. He had a mini-fridge for us and it included two bottles of water and juice for us to drink. The kitchen also had a microwave.
Bathroom: He provided plenty of towels. The toilet, sink and shower worked well. There was good water pressure in the shower and hot water always available. He also had a washing machine and laundry soap available.
Other: The building had an elevator, which was convenient for our luggage but otherwise we used the stairs as it was quite old.
CONS
Bathroom: There was a faint scent of sewage that we could not get rid of no matter what we tried. I think it was coming directly from the toilet (perhaps the building used a septic tank system).
Check-in: The place is advertised as 24-hour check-in BUT THIS IS NOT THE CASE. Check-in was at 2pm, though he did tell us the day of our arrival that we could go a little earlier. ALSO we had to pick up our keys at the Hotel Madrisol up the street, which was a little inconvenient. When we arrived the person at the desk spoke no English so it took some time to get the keys from her. When she realized we were staying at the airbnb she just handed the keys over, no questions or ID which honestly seemed a little unsafe.
Other: There was a small club directly across the street that was extremely loud until 4 am every day (even Sunday!) - but the sound cut off promptly then. It didn't bother us but it might bother some people. We could hear virtually every word from our neighbours.
OVERALL
The only main complaint would be about check-in. The property was falsely advertised as 24-hour check-in in the title. We never met Helios but he was very responsive over the app and the place was clean and central.