We loved our stay at Caroline & Philipp. The appartment is well decorated and very "Berlin". It is on the 5th floor, though; I strongly advise to reconsider if you have a child(ren). Also, this flat (and almost the whole building apparently) is dedicated to airbnb, if you're looking for a more "authentic" experience.
Caroline sent us a generous list of places to go, around the flat and further (restaurants, bars, and else...) that we used a lot! Her advices were always on point, and in Berlin where you can easily get lost with the number of cool places, and the size of the city, it proved very helpful!!
The flat is a little more expensive that other offers in Berlin, but can be worth it depending of what kind of experience you'd like...