This was my first trip to Stockholm and it is an impressive city. I stayed in Katia's flat in the old town with my 2 teenage daughters and it is hard to imagine a better base. Essentially all major attractions are within easy walking distance or by taking a bike. If you hire bikes for more than a day there is an area in a central court within the building where they can be discretely locked up.
The flat is well presented and as shown in the photos. It's light and airy with a fully equipped kitchen kitten out with all devices (microwave, modern oven with ceramic hob, toaster) / plates bowels coffee machines you could possibly want. There is a Nespresso machine so bring pods if you want though also a filter machine - or just go out and go to a cafe. The shower has good pressure and water temperature. It is easy to find though I would highly recommend walking round on the main road past the Royal Palace which has a smooth pavement rather than dragging suitcases over the cobblestones of the old town. Much easier to navigate initially as well. We took the Arlanda express to the city and it till between 20-25 minutes to walk to the flat - really not a big deal as you are passing by major sites and then into the old town itself. Entry / finding keys was straight forward. The flat is warm and has cable TV if you want to use it. Wifi speed was excellent with easy connectivity. A selection of city maps / info on attractions was left by the TV which was useful.
Katia was very helpful and accommodating responding promptly to emails etc. We didn't meet but I got the impression that had there been a problem then a solution would have quickly been found. She was also available for advice had we sought it.
All in all this is a great place to stay - it's super central, clean, well presented and greatly added to our city break in Stockholm.