We just stayed 4 nights in radisson blu. I booked it with the US bank certs. Was told upgrade was not available when we checked in because the hotel was pretty full. We asked about breakfast and was denied. We asked to talk to a manager about it and was given free breakfast since both me and dh are gold. (We asked because we were just given breakfast by front desk agent of radisson blu Berlin due to no possibility of upgrade, without us asking). This perk is really convenient for our daughter. Breakfast was ok. Hot item included sausage, very har/ chewy Canadian bacon, scrambled eggs, haggis/blood sausage, beans/mushrooms , and kind of soggy hash brown. You can order smoked salmon egg Benedict and hot cereal from the waitress too. There are different variety of pastry/bread, cereal, yogurt, and fruit.
I believed we got some kind of upgrade from our original booking, even though they said they couldn't at Checkin. Our room was on a high floor over looking rooftops to the sea and Arthur's Seat. It felt newly renovated with nice modern decor and lighting. Room was not big but it's Europe. I can see there are many rooms facing the dark drabby interior courtyard which I'm glad we didn't have to stay in. Of course, the location is perfect. Overall had a great experience and would definitely return.