We enjoyed our one-week stay with two adults and one child (five years old) and whilst the kitchen is small it was okay for our purposes and we were able to easily prepare breakfasts and evening meals.
The apartment is in a very good location for exploring Stockholm - just three stops directly from T-Centralen and four from Gamla Stan. We'd recommend picking up an SL travel card to make getting around the city cheaper - there was an information desk in the airport arrivals hall where we bought our seven day travel card.
We explored the city centre, Gamla Stan, Vaxholm (via the commuter ferry), Haga gardens and Skansen during our stay, so there was plenty of activities within easy reach.
Our five year old also enjoyed the playground that is a short walk from the apartment.