It was a nice hotel. The room was nice, and staff were helpful. Air conditioning worked well, and the nights were quiet. Breakfast as good, even if there was the same content whole week.
The location of the hotel was on walking distance to everything, and the closest railway stop was 800m away. Closest Rewe (super market in Germany) was within walking distance also, which was convenient.
As we visited the city for the Gamescom, we had no time of energy left to use the hotel's sauna and gym. Checked them out on first day (downstairs on basement level) and they looked OK.
If I'd have to say something negative about the stay in this hotel, I'd say the minibar was noisy, and the light shining from the air conditioner was really bright. But that's just nitpicking.
Probably would use this hotel again if we'd visit Cologne again in the future.