A lovely apartment in a fantastic location. The nearest station on Berlin's excellent U-Bahn system is just a couple of minutes' walk away, as is Ziervogel's Kult-Curry, which Henrik and Sven's very helpful guide recommends as the best currywurst in Berlin (and it was VERY good, including the vegetarian version) and the brilliant Zeit für Brot, where we ended up eating every single day. Even if you prefer walking, Alexanderplatz is really close by, and it's right in the middle of Mitte, a lovely part of the city.
The apartment itself is the perfect hub for a city stay – cosy and welcoming but with plenty of space to relax, a kitchen that uses its space perfectly with loads of equipment, and the bathroom was clean and easy to use (that sounds weird. It's weird trying to describe a bathroom. But this bathroom was very good!).
Henrik and Sven were excellent hosts – we only got to meet Sven, but having one of them next door every day was very reassuring, and Sven was very helpful when he welcomed us. They also provided a guide to the city which helped us plan our time there perfectly.
If (when) we come back to Berlin, we'll definitely try to stay with Henrik and Sven again!