This is a good apartment, but some issues need improvement (based on my 5 days stay at this property).
Positive points about the apartment:
Spacious apartment with lots of natural light: spacious living room, bedroom, bathroom and kitchen.
Modern kitchen and bathroom (with shower rather than bathtub)
Really well decorated (the hosts are architects), giving the place a unique character
Good location and neighborhood, near supermarket, and you can even see the river from the apartment.
Issues that need improvement:
The host IGNORED and NEVER REPLIED to a question / request I made on the second day of my stay, which I consider unprofessional and impolite. Details: I asked the host, via the Airbnb app, if the apartment had an extra towel, because my spouse needed another towel to dry her long hair and we only found 1 hand towel and 2 bath towels for the 2 of us. I never got a response, but I know the host read my question because the next day, more than 24 hours after I wrote to him, he saw my spouse coming to the apartment and asked her if we still wanted another towel, but by then we had already gone to a store to buy a towel (note: the host did not apologize for not replying or even acknowledge it).

The shower only has a small hand shower head (that is, it has no fixed shower head) and the piece that holds that small hand shower to the wall was BROKEN, which the host did not mention when he checked us in - I expect hosts to be frank and tell me when they know something important is broken in the apartment, rather than leaving me to find it out. Once I found this was broken, I asked the host about it (this was the only other time I asked something to the host), he apologized that he had not had the time or the tools to fix it and suggested I support the shower head on the handle, which did not work since the handle is only 3 feet from the ground. The host never fixed this during my five day stay, so we always had to take showers holding the shower head in one hand, which can be done but is really inconvenient and impractical - even more so if you have long hair.

The mattress in the main bedroom was thin and too soft - the type of mattress you might get at a 2 stars hotel - so it was not comfortable to sleep, as it did not provide enough support. (For comparison, I stayed at a 3 stars hotels after this property and the mattress was much more comfortable).

There was nothing to dry the bath towels and, being winter and humid, after the first shower the towels always felt damp. Most properties in a place with this kind of weather would have at least an electric towel rail, which can cost as little as 30 euros.

There were other smaller issues that also made the place feel like a 2 stars accommodation, when it has the potential to be a 4 stars:
The entire apartment only had one heater.
The hosts provided only two bath towels and one hand towel for a five day stay (and these were cheaper towels than I usually find at an AirBnB)
There was a bucket to be used as a trash bin in the kitchen, with no lid (so the trash smell is not contained).
There was no trash bin in the bathroom (you have to walk to the kitchen every time you need to throw something away, like dental floss)
The silver lining here is that the hosts can fix all of these issues, which I hope they do, and most of these issues cost very little to fix (responding to guests when they ask a question, for example, costs nothing).