I had a pleasant stay at Nena Apartments Hermannplatz. It is in a great, central location, close to the metro for easy access to other areas of the city. The studio was very spacious and immaculately clean. Comfortable bed and great amenities included (fan on hot days was a nice touch).
The only couple of things of note included:
1) upon check-in, I noticed that I was not provided with any soap (no hand soap) and the shower soap dispenser was empty. I was able to rectify the issue but contacted your concierge onsite who was quick to supply the necessary supplies.
2) I don't recall the description of the place mentioning it was on a busy/noisy street - which was a slight disappointment. I was grateful for the sound-proof windows, however.