The location is great, just literally steps from the Ubahn line even though the flat is actually in Moabit when the headline says Mitte.
The flat is nice and spacious with fun decor. There was some TLC needed with the older place (shower closure was broken and the kitchen light did not work) but otherwise seems very well maintained.
The WiFi is not good in the building though, we had a hard time connecting to even be able to pull up google maps to get directions. We brought our own pocket WiFi hotspot as well, and even that did not have good reception inside. So if you are depending on the internet for researching where to go (or needing it for work) this would not work out for you.