Jan's apartment is everything you would need for a short/longer term stay. The location really can't be beat, it's close to many clubs and cool bars that are walking distance away.
I stayed at the apartment for a month and half working remotely and it was very comfortable to spend a lot of time inside if I needed to, but there were so many cafes nearby I could easily take a walk and find another comfortable place to work remotely.
The nearest U-Bahn station is a 3 minutes walk away and a good line to be near as it connects to many other destinations you may want to visit in Berlin. I locked my key inside one night and Jan responded quite quickly from India! Thankfully his friendly neighbor (Axel) also helps out and he was able to let me into the apartment very quickly. Crisis averted!
Overall the stay was great and I would absolutely consider booking again if I were to need another place in Berlin. Thanks again!