We really enjoyed our stay at Annika's apartment!
It was well equipped, the kitchen has everything you need, the beds were comfortable and everything was nice and clean, and the wifi gave us no troubles and was very reliable.
Location wise, it has two stations very close by that connect you to anywhere you need to go, and there is a convenience store very close by. Checkout was also very easy.
If you're looking for a slightly longer stay, and want a good location, lots of privacy, great price, and a very friendly welcome, we recommend this place a lot. If we ever return to Berlin and need an apartment for two, we would love to book it again.