Jun's place is perfect, it's a nice modern apartment with a huge main bedroom/living area and nice bathroom. The location is very good with a new supermarket next door and plenty of restaurants and takeaway places nearby. Stops for the M4 and M10 trams are both 5 minutes walk so it never takes long to get anywhere within central Berlin.
The only people I wouldn't recommend it for is anyone with mobility issues as it's up 3 flights of stairs. For anyone else, it's a perfect base in Berlin.