We booked the Pestana as we wanted a fairly good base to explore Berlin from, but wanted a bit of peace and quiet too. As it is in the diplomatic district, it is ideally placed if this is what you want too.
The rooms were very clean, very well-designed. We loved the bathroom with its big shower and window into the main room. We had a lovely view over the Tiergarten. The bar was pleasant to sit in for a final drink of the evening, and the breakfast provided a wide variety of different foods to choose from (I wouldn't recommend waiting to have your own breakfast as there are not many places to eat nearby).
The desk staff were really helpful - booking taxis, hiring bikes etc. If the weather is good, the best thing to do is hire a bike and cycle through the Tiergarten. Lovely. I would definitely recommend this hotel to anyone doing a city break to Berlin.More