The apartment has a very good location, near to National Museum, near to public transportation, restaurants and super-markets.
I've stayed with another 3 people in it, and it was big enough for the four of us.
We had anything we've needed, except of a hairdryer which the owner offer to buy (the previous one was broken from other visitors), but in the end we managed without it.
The only minus that comes in mind are the wooden floors , the doors and the beds which are kind of noisy. The apartment is in an old building, and even if it has modern finishes and furniture, the floors and the doors are the old ones, and those make loud noises. Also, you can hear the entrance door from the building every time it closes, because even if it has a hinge that closes it slowly, in the end it closes with a loud hit.
The owner was very nice, the communication was good, and he responded quickly to my messages. I think a self check-in system it's needed, because it would be easier for everyone.
Overall, it was a good decision to rent this apartment!