e: too loud, waste of heat and space, etc. have already all been mentioned in the thread. We all know them as well; they usually come from people who have never experienced the spatial and living feeling of a vertically open living space for a longer time.
We ourselves have an open space... and my husband often watches TV longer than I do.
It is actually too loud for me: the sound carries upwards, as if I myself am watching/hearing TV upstairs.
No offense to your kind words to the OP, but even if you have built something like this yourself, not just a standard 0-8-15, you have to admit what drawbacks lie behind it.
South-facing orientation in modern energy-saving ordinance buildings means: after 10 minutes of sunshine: blinds/shutters down, otherwise it becomes a sauna. You can wonderfully observe this in all new residential areas: hardly a house where it is not consistently darkened and shaded daily as soon as the sun shines. Then one asks: what is better: free view and scattered light
That is exactly why we built all the terrace windows in the open space facing east, south, and west. Small windows in the north. Otherwise, it wouldn’t have been a KfW55 house just like that. The shutters do not go down during the day in order to let in the solar heat. We love the sun and accordingly built that way.
But this is not about us, not about your maisonette apartment, not about my house.
It’s about optimizing the OP’s planning. Otherwise, he wouldn’t have asked here. So why should one sugarcoat everything when so many negative points can be named? That doesn’t help anyone.
I and other critics here don’t have to move in or pay off the loan for some misguided planning.
So then....