Thanks your your comments
You are absolutely right about the chair. I didn´t think of that

... an neither did design connected

Mhhh ... I would like to model some kind of holding to the metal of the chair and just make
a region render of it ... wait, won´t work. I still don´t get, why region render is still not implemented,
but thats another topic.
I really worked on the floor, which is supposed to be a old wooden board floor. I have a lot of reference
material. The glossy is mapped and I tweaked it a lot. It look strange when the floor was more glossy, more
like it would be wet. This would look good on a more modern floor material but on those old boards I tried
to make it look, like the last wax, that was put on almost dried completely. Thats why I chose the glossy to be more smooth. Take a look at the reflection of the lamp on the right. I think it is perfect for the kind of wood material I tried to create. In my opinion more gloss just looks too polished and wet for this kind of old wood texture.
The plants have a sss shader. I think the "problem" is, that there is noch light behind the plants. It looks completely different when you put the plants between the camera and the windows. I looked at the plants we have here at the office and there is almost none SSS visible when they are standing in front of a white wall.
And in fact some of them look like plastic

When you make the SSS effect stronger it looks more like basil, which has much thinner leaves than the plants I tried to imitate.
The metal of the chair has scratches. But they are very subtle, you can only see them if you soom in on the 4k resolution. I had them stronger in the beginning, but this too didn´t look right. The metal seemed too used and old. Chromed steel doesn´t really get really used or old in my opinion. The scratches are there, but they are too thin to see at this distance in a 2k picture.
Don´t get me wrong. I unterstand your points completely and I´m glad for the feedback. It is just, that I changed this points over and over again because I wasn´t sure specially, after everyone here at the office said something different.
Like for example, the plants look too much like basil or the floor seems to be wet
I think you´re right about the gaps between the boards though. May be to extreme.