Location is great, and the full automated check-in process (including door unlocking) is pretty nice. The only pitfal is that if you don't have internet in your phone things might be complicated to open the apartment for the first time (since you unlock it via the app).
The appartment was clean and organized. The kitchen appliances are not great, and there are just few tools / utensils available. But no big deal.
There was some confusion during the stay extension request I made. The initially communicated price for one extra night was not fulfilled and the city tax per night per person (initially charged as 3.30 euros) was increased to 4.40 euros and I got a surcharge in my credit card.
In general the great location compensated the troubles, so I consider this stay as OK.