The four-bedroom apartment is just two two-bedroom apartments with an adjoining door (one apartment opens directly onto the quiet street, the other is accessed from an internal stairwell area). This isn't a problem so much as it just comes with some quirks, like there's no obvious "loungeroom" for a larger group to gather in and no full-size kitchen, just two small kitchenettes.
Between the two apartments, there are two shower rooms with toilets and an additional guest bathroom. The couch (in the rear apartment at least) is really not great for sleeping - it's just four square cushions laid next to each other which means your back naturally goes for the gap in the middle.
The adjoining door between the two apartments is alarmed and has a tendency to go off if you don't make the effort to close it very gently.
There was a fair amount of stuff in the back apartment that wasn't cleaned very well prior to our stay (think grease on the stovetop, empty wrappers in the cupboards, and dried milk scum on the coffee machine) and there wasn't much general use stuff like hand soap or toilet paper so we had to buy a lot of that which is unfortunate for an otherwise quite nice Airbnb. With a little extra care and attention to detail this could be a nice space.