This is a great place to stay in Berlin. The location is pretty much ideal - it is within walking distance of so many interesting places to visit and public transit routes.
The apartment is very cute, clean and comfortable. Vlad and Kristina are prompt at responding and clear in their communication.
The only caveat is that you do need to go an extra stop up the train line to pick up the key. This can be kind of tiring as an additional step after a long day of travel.