I spent one week in Malta with a friend, and we stayed in Mark's apartment. Best choice ever! The apartment is located in a very quiet neighbourhood in Sliema, but within 10/15 minutes walking it's possible to reach Saint Julian and Paceville with all the restaurants, bars and clubs. The bus stop is just around the corner, with buses going to Valletta, the beaches and even the airport. The apartment is equipped with all the facilities you need, making you feel at home during your holiday.
I didn't meet Mark, but the communication with him to organize everything has always been quick and very efficient. Check-in and check-out were really easy and well organized, with the helper of the house.
I definetely recommend this cozy apartment if you plan a holiday in Malta!