A very nice organised small apartment in a very nice neighborhood of Kreuzberg.
The check in was easy and fast.
Our host was really good, helped us with everything we needed and had the apartment waiting for us in an excellent state.
The flat is not big but it is designed so good it contains everything you'll need for a short period trip to Berlin.
The only thing is that shower is a little bit small for tall people (but you can find your way).
And as the host has mentioned on the details of the apartment some nights may have some noise that can be a little trouble for light-sleepers, but it didn't bother us at all.
In general I am thankful of my choice and my girlfriend and I really had a good time in Berlin and in studio X. I totally recommend it!