The apartment was in a great location, located by the subway (Rosenthaler Plat) and many restaurants. My husband and I chose a 2-bedroom apartment for us and our three boys (ages 13, 11, and 9) and it was perfectly large for us all to sleep comfortably. The communication from the front desk for check in was amazing. Rather than a check-in during business hours, they were able to send us online codes to check in and it was an absolute breeze after taking an 8-hour train from Paris.
There are a few downsides to this apartment (and the others in the building, I assume). One would be the beds inside of the apartment. They were incredibly firm/hard, and by the end of our five day stay, my back and neck were in a lot of pain. The pillows were also not great, not nearly enough support.
Another complaint was the level of street noise. While we LOVED the view of the street (we were on the fourth floor, and while there was no balcony, there were large windows), the noise from the street was very distracting, especially at night while we were trying to sleep.
But there is air conditioning, which is a huge bonus when you visit during the summer. There is nothing better than air conditioning after walking around Berlin on the hot days.
Overall, we really enjoyed our stay in Berlin and at the Rosenthal Residence Apartments. With some small improvements, we would very likely stay again!