The satisfaction with ArtHotel Connection very much depends on in which room you're staying.
The first night we (hetero couple) stayed in a 'standard room' which was small, not very stylish and had a terrible (old) bathroom. From the second day we switched to a higher category and got room number 6. It was like entering another world: stylish, huge, clean, with a very nice (small but new) bathroom. Room number 6 I would prefer even over a room in Regent Hotel.
From the second day we loved the hotel, were happy about our choice not staying in one of the typically huge 5* hotels. The complete building, the old elevator and the very friendly service.
WiFi is very good, but the best point is the breakfast. It's principally served whenever you want. And at EUR 10 it's perfect, very good German bread rolls, a good selection of cold cuts, jam, honey, fruits and even eggs-to-order.
When next time in Berlin we'll stay at ArtHotel Connection again - but straight away will chose one of the good rooms.