We stayed at Jo's apartment to go to the Viking ship museum and see a little of Oslo centre. Its a lovely big space although note that its open plan so there is no separate bedroom if you want to put the kids to sleep in a separate area. The location is amazing - very close to the museums and not far from Oslo centre. There is a ferry which departs from nearby and goes over the bay to the centre - unfortunately you cant buy the cheaper return ticket on the boat or before you board from this side but its still worth doing. Failing that its only a few minutes walk to the bus stop. Highly recommended and if we come back to Oslo I'd certainly consider booking it again