Sören is the perfect host; punctual, welcoming, warm, knowledgeable, and generous! He met us at the apartment, told us everything we needed to know and answered a few of our questions about Berlin in great detail.
The apartment itself was spotlessly clean and well furnished with almost anything you could need. The flat is great for large groups, with 2 bathrooms and 2 kitchens, it's easy for everyone to get ready in the morning. Just 2 minutes from the S-Bahn station and around 3 minutes from the underground, it's also in a great location for being able to travel around the city. There are plenty of shops, cafes and restaurants nearby.
I would cannot recommend Sören's place enough; we will definitely be staying with him again should we return to Berlin.