Can be a reasonable option for short stays but not for the longer ones.
Mariella's apartment is not a good place to stay for a long time. We stayed in this apartment for 3 months and it´s very uncomfortable. The apartment is very dark and there is no daylight. It´s necessary to keep the lights on all day.
The windows are not good for circulating the air, which makes the place stuffy. We were in this apartment during the winter which made the experience worse. The floor is cold, the shower is not good and in the ad Mariella reported that it has central heating but it is not true. Has a simple “floor heater” and that doesn't work properly. The internet also does not work well, quite unstable.
But, what makes the things really worse was the fact that Mariella tried to charge us 3x times the right amount for the electricity bill. My wife and I needed to find a government calculator to show her how abusive was the price she was trying to charge us. After that, all the relationship we had was ruined once we didn't trust on her anymore.
Another annoying thing was the fact we were about to leave the apartment in the beginning of the outbreak of the Coronavírus, she didn't look to care too much with us. Just said we would must think to leave as soon as possible once a lock-down would be eminent.
We have visited almost 20 countries in our lives, many of them through Airbnb or hostels, and it's really sad to think unfortunately it is the very first time we haven't had a pleasant relationship and also not being able to carry good memories from the place.

The positive point of the apartment is the location as it is close to supermarkets, pharmacies, cafes and close to St Julian’s Bay.
Lastly, analyzing positive and negative points, I think it´s not a good deal. It´s better to look for a better place.