spent 3 nights there in a business trip just before xmass, but with my wife who is interested in the berlin monuments.
as such, i believe it was an excellent and budget-wise choice: the interior is nice, rooms well design-like equipped, and - especially - the staff is extremely attentive but not intrusive which is making the stay a very pleasant experience. location is just brilliant - walking distance to potstdammer, musem insel, topografie des terrors, etc.
breakfast and internet are overpriced (i never understood why in germany, wifi in rooms is not part of the service), but there is plenty places around where you can eat cheap and connect for free. for a dinner, the choice and quality of meals in the hotel restaurant is what you would expect - not cheap, but very tasty.
highly recommended!
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC