Unfortunately, we had an awful experience with Marcello's loft. We have listed the problems we encountered during our stay:

1) The air conditioner was broken, so it was difficult to sleep during the night due to high temperature (the apartment has only one window, which is on the street level, so we kept it closed so people did not see everything inside the apartment).
2) The water heater thermostat was broken.
3) There was a cold water leakage above the toilet.
4) The shower had a terrible urine smell and signs of lack of hygiene.
5) Overall, the loft was not clean.
6) The communication with Marcello or his assistant Lavinia, was not good.
7) The duvet had a red stain on it, with terrible signs of wear and lack of hygiene. Seriously disgusting.
8) The check in was delayed on more than 30 minutes, and we were left outside on the street waiting for the keys. Upon entering the loft, our first impression was that the place was not being well taken care of.

The only good aspect of Marcello's loft was the location. It's undeniably well located, 3 minutes away from Piazza Navona and less than 10 minutes away from the Vatican.

Moreover, we would not recommend Marcello's place, and we would not stay there ever again.