It's clean, it's well run but it's not a hotel, it's a hostel which would be suitable for anyone on a tight budget or teenagers backpacking around Europe but it should not be classed as a hotel.
It's small, cramped, and the single rooms are more akin to prison cells, it's lacking air conditioning which means the windows need to be open 24 hours a day in the summer, and it's proximity to the 'Dom' makes for a bad nights sleep when the bell is chiming the hours.
Bed's are small and uncomfortable, and during times of high demand (trade fairs at the Koln Messe) the prices (like any other hotel in Cologne) rise steeply. For real hotels this may just about be defensible, but for this place the price rises are way beyond anything which would pass for acceptable given the quality of the accommodation.