Great experience!
The apartment is large and clean, located almost in front of Magdalenenstraße metro station U5 (1 min on foot) and it takes about 10 mins to get to the city center. There's everything you need around: shops, pubs, laundry and so on. There are 3 double size beds and 2 single size beds (all really comfortable) and one bed/couch (comfortable as well), 3 bathrooms (useful if you are many) and a kitchen (watch out: fridge isn't big, but it's no problem since there's a LIDL at the other side of the street).
Michael is kind and helpful, he provided us everything we needed: maps, brochures, basic tools and spices for the kitchen, linen, shower stuff: a perfect apartment. Plus he was available anytime, which is really nice!
Nothing else to add, I recommend the apartment with no doubt if you're thinking about a trip to Berlin.