We rally loved staying in Cornerstone. It is very well locate, close to restaurants and less than 10min walking from the boat to Valletta. The apartment is fully equipped and modern. You have everything you need for a short stay. Even though I did not meet Audrey face to face, she was very responsive and never took more than 5min to reply my questions.
The only downside is regarding parking. Sometimes is very hard to find a place on the street.