My stay was great! Transport was relatively easy, checking in/out was a breeze, and it was a perfect location for the Weihnachtsmarkt at Schloss Charlottenburg.
There were a few small inconveniences which did not detract from my stay but could negatively impact others- namely sound from the street and folks on the other sides of walls, light from the gas station across the street keeping the studio pretty well-lit at night (I could see to go down the stairs with no issue), and being unable to stand up straight on the platform the bed is on (I'm 5 foot, 7 inches tall). All was easily dealt with, but others may take issue.