The Hilton Cologne is all in all a nice hotel. Slight drawbacks include the lobby - you are not entirely sure whether you have entered the local council, or a high profile hotel. Luckily there is a nice looking restaurant on the left to bring you mind in the right direction.
When we arrived there were lots of people. According to the helpful receptionist they would soon be all gone - they were apparently only visiting the hotel for meetings.
Despite reminders they forgot to make our extra bed for several hours. The next day (we stayed two days) the staff did not arrive to clean the room until it was to late.
The hotel has a splendid position, next to the Kölnerdom, and the rooms were really nice. When it comes to the small glitches I take it that there might be a problem with finding enough staff, as with so many other hotels.
What they should do with the lobby which looks as if it belongs to some communal branch, I am not completely sure of, but there is certainly potential!
All in all: a nice hotel, with some parts that should be possible to address without to much expense.