We stayed there with our family with 2 kids. Everything was great. For Malta, I would say you need a car to get a better sight seeing or go the beach (better and easier than bus - which is also available and lots of tourists use it).
Helen is a great host. She gave us all the information we needed. The apartment is a very spacious one, and well equipped - the kitchen is new. Internet connection is very good. It is located in a residential area, quiet. It has 3 bedrooms, one living room with kitchen, and one bathroom.
Rabat center is close by walk. We used to run around the city during the mornings. St. Paul's catacombs are there too.
There are some local shops near by. If you want bigger ones, you need to go to Lidl in Mosta - about 8-10 minutes drive. We used to buy fruit and vegetables from the locals - Maltese products - either on the side road for which we got the best price and quality, or in stores of the locals that sell only that.
Mdina is near by, a nice fortified city to visit and walk during the evenings. It has some restaurants inside and kids playground at the main gate. You can't drive inside, so either leave the car in the parking or streets nearby or walk from the apartment - not far.
Closes and best beaches are Ghajn Tuffieha and Golden Bay - about 15 minutes drive or less. You definitely want to hike the short path in Ghajn Tuffieha beach, and you will get a splendid view of the surroundings. Mellieha Bay is a little bit far, about 30 mins, but is great as well. There are lots of other places to visit, still with the kids we had limited options.