So this apt has the ultimate way to manage the "key exchange", and you can arrive and leave whenever you want, 10 out of ten.
Room, kitchen and bathroom were clean, and the forniture is pretty new. The apt is located 5 min from Kaiserdamm metro station (U2) so it's super easy to reach.
The only thing that disappointed me was the Wifi connection (2Mbps is too slowly even for text messaging).