The apartment was cosy, warm and clean. It was ideal for 6 of us as there was alot of space and also a compact kitchen complete with crockery, toaster and cooker. The bathroom is lovely however we had a bit of an issue with the drainage meaning the bathroom floor became flooded at times, no doubt this is simply due to a blocked drain. We found the apartment noisy at times due to it being an old building which did perhaps interrupt sleep sometimes, but due to the nature of the age of the building this was inevitable.
The apartment was easy to find (right in front of Birkenstraße U-bahn) with links to the city. You can also take a direct U-bahn here to Zoologischer Garten to change onto the Airport Express for Schoenfeld airport.
Overall a great spot for a group, clean, functional and cosy!