It was a pleasant stay in the apartment. A couple of days before arrival Raphael contacted me to ask me when he could expect me, I gave him an approximate time and we agreed that I would contact him 1 hour before arriving.
When I arrived, Raphael was very helpful, he walked with me to a so called 'Trafik' where I needed to buy a parking ticket and he even helped me carry some stuff from my car to the apartment.
The apartment is small but cozy and enough room for me alone, the small kitchenette has all appliances you need, although I didn't use any of it except the fridge. Also the fast WiFi is a nice service which made my stay more pleasant, this allowed me to do some research about the things a saw or went to see.
The connection with public transport is very well, there's a S-bahn stop a couple of minutes away from the apartment and the west station is only a 10 minute walk. With the U-bahn it's about 15 minutes to get from Westbahnhof to the city centre.