I stayed in Grit's place for 10 weeks while in Berlin for business. I think it represents excellent value for the price. It is literally right beside Hermannstrasse s and u bahn stations giving you access to the whole city.
The flat has everything you would need and is surrounded by food options, supermarkets and 10 minutes from the tempelhofer feld.
The only negative was the thickness of the walls in the bedroom. I felt prepared for this from reading the other reviews but it is little solace at 4am on a Thursday morning when you're woken up by techno :)
The noise is obviously beyond Grit's control and she is an excellent host. Great communication from start to finish and she even let me use her bike, which was a great help for me.
Would stay here again for sure.