We have stayed in the cottage for 10 days with 3 adults and 2 kids (1 baby). We have had a great time. The house has everything a family needs. The outside patio has a large dining table and two sun beds. The living is very spacious and light (windows on all sides). Also the location is perfect. You can walk to the beach and local restaurants (good coffee place around the corner that opens at 7am). There are many kids friendly places close by like The Clay Cafe, Black and Brewery, Dunes, Vine etc. By car most highlights in the city and Constantia are within a 30 minutes drive.
Conclusion: great place to stay (with kids) to explore Cape Town and around.