I've stayed at Jack's and Anna's place with two friends for about a week. Everything worked perfectly. The check-in instructions were clear and all our questions were answered within an hour or less.
The flat was clean and heated upon our arrival. It is spacious enough for up to 6 persons and situated perfectly in the city centre.
Two of the bedrooms are a bit noisy for their windows go to a main street and also there's a bar downstairs. But the noise wasn't an issue for us and we considered the bar a big plus.
All in all I can highly recommend Jack's and Anna's place.