I stayed with my family at Katia's apartment for 4 nights. The apartment is perfectly located, so all the Stockholm's attractions are within the walking distance. The apartment was spacious enough and clean. It was equipped with everything we needed during our short stay.
Our host was away during our stay, but we arranged everythig via emails prior to our arrival. Katia also made clear we could contact her should there be a need for it.
All in all I would whole-heartedly recommend staying at Katia's to everyone.
best,
Predrag