We loved our stay in the flat, and it was a great location. Just below the flat are an organic food store and bakeries, and it's round the corner from the metro station. Very quiet and peaceful at night too.
We had a bit of trouble getting the door to work at check in. The keypad on the door of the flat never actually worked for us, but luckily there was also a way to unlock it using our mobile phones. We did worry about getting stuck if we mislaid our phones or the Internet wasn't working though!
The only other slight negative, was that the bars on the front of the terrace were too wide for us to feel comfortable letting our 2 year old play out on it. This wasn't such a problem for us, as we were there in February, but in Summer it would have been much worse. It's fine for older children/adults though (and it's a great terrace).
Altogether we had a lovely stay, and I've already recommended the flat to a friend and her family!