I've just checked in today and haven't fallen in love with the place.
First impressions - no doormen and when I eventually make eye contact with a receptionist who is on the phone I get a series of rather direct and unfriendly hand signals telling me to go away.
On check-in I get an upgrade from a base level Deluxe Room to a "Superior Room" on the top floor facing Under den Linden. Looking at my floor plan it's one of the smallest rooms in my area of the hotel. I'm thinking they perhaps took my "away from the elevator" request literally as it's the final room down quite a long corridor. There are no suites available online, but two types of Superior room above the one I was assigned.
The room is modern and of acceptable size, as you'd expect in Berlin. There is a plug on either side of the bed, though one rejected a standard German plug converter. Overall the room seems fine.
The bathroom is a bit weak. Weedy shower (perhaps the new Westin model?), apparently almost no ventilation and two very small towels which when they get wet give off a strong and very unpleasant smell (washing at wrong temperature?).
It's a good location and is a perfectly acceptable business hotel, but I can't see anyone becoming particularly fond of it.