We stayed at the apartment in the summer of 2016 with four people (two couples).
The hosts are very well organised, very prompt in their communication and gave very clear and helpful instructions for our arrival, and even gave us the wifi password for internet access at the meeting location.
The apartment is lovely. It is well equiped, attractive and in a wonderful central location.
It is big enough for two couples, and the sofa bed is quite comfortable.
Two things to be aware of:
1. The apartment is on the top floor and the stairs are relatively steep and narrow. Additionally the stairs to the loft bedroom are very steep and narrow.
2. The street outside has an active nightlife and can be very noisy. The double glazed windows keep it out, but during summer you'll likely need to keep the windows open.
We had a great time at the appartment and would definitely stay there again.