The Vodaphone hotspot that you pay for weekly was unreliable and made our trip much more stressful, because it didn't work at critical times.
The apartment was clean, but not well stocked, we ran out of toilet paper and dish soap during our stay.
We were asked to leave the apartment exactly as we found it, despite paying a significant cleaning fee. We certainly wouldn't have left a big mess, but we felt the check out instructions went above and beyond the usual. We also didn't receive the check out instructions until we were already at the airport, due to the unreliable wifi, but left the apartment decently clean, with most rubbish gathered by the door.
We also had to pay the Berlin city tax separately in cash, which has never been my experience with other apartments in Berlin.
The location is great, with beautiful balconies, but overall feel that the apartment would only be worth it with private WiFi and fully stocked amenities.