We stayed 2 nights in the Radisson and then we had really enough of it. Internet was still down for more than 24h when we checked out. Elevators are annoying and irritating and stairs can only be used in the event of emergency (there are stairs but clearly a no go according to the hotel management. Why ? Nobody knows). And definitely do not stay there because of the aquarium which is a nice attraction but out of order for several months.
The rooms are not in a good shape and what is the most irritating, is that you cannot open a window and put down the heat. It was at least 25 degrees in my room and there was no way to make it fresher. Avoid at all cost the rooms without an external window (half have a view on the lobby without access to any fresh air, stay tuned for guaranteed claustrofobia).
The whole place was truly annoying : no internet, no telephone reception for our carrier, elevator issues, heating/cooling issues. This is a badly managed place and I strongly advice to avoid this place with lots of other great hotels in Berlin.
