This was our first visit to Prague. Also, it was my children's first trip abroad. The apartment was perfect for this trip. It serves as a good hub for easy, short walks to many different restaurants and attractions, and it's close to several public transportation stops. We were right between the children's favorite parks (on the other side of the bridges), and the places we wanted to visit (to the east and north).
With three pre-teen children, the washing machine was key to the success of our trip. We did carry-on luggage only, no checked bags, and used public transportation or walked everywhere we went. We wanted it to be a bit of an adventure for the children.
If you have larger luggage, I would recommend getting picked up by car from the airport. The cobblestone streets and stone sidewalks might be more than enough reason alone, then you can add the difficulty of trying to wrangle multiple bags on the potentially crowded metro.