The appartment is great. It is spacious, clean and in a great neughbourhood! We were with 8 girls and had all the space we needed. It was close to a metro, so easy to go around Berlin.
What could have been better is the communication. I did send several messages in the weeks before arrival with no response. It made me worry a bit. Only in the week of arrival we did get reponses. The check-in in the end went good, we arrived after midnight at that was no problem. Checking out was a bit strange. 10 minutes before the set check out time (11.00) a lady already shower up starting to clean while we were still in the appartment. Outside the next group was already waiting..
So communication and check out could have been better, but for the rest the appartment was very good!