This is a great part of the city, and Robert's apartment is perfectly situated and easy walking distance to many fun, interesting tourist and non-tourist activities. Robert's checkin details were easy to follow and accessible. He also let us drop our bags off earlier than normal checkin time when he learned when we were arriving, which was very thoughtful and helped us!
If you have trouble reaching him through the app, I suggest texting directly or through WhatsApp. Once we reached him, he was responsive when we had questions or needed things addressed.
Make sure you're prepared for a somewhat narrow, 3 flight walk-up. Two flights to get to the door, and one more flight once you're inside the door. This worked out fine for us, but if any of us had mobility issues I could see it being challenging.
Finally, upon arrival make sure you have enough towels and toilet paper before it's too late to ask about it. Also if you need to use the washing machine, we had to find the instruction manual online, but eventually we did. These issues were fairly minor compared to the convenience and ease of access to a fun, vibrant part of the city!