This render’s so bright, I gotta wear shades.
Is that a door on the left side of the couch? That is a wierd architectural detail with the shelves in between those big windows and the door.
Could use a little more geometric detail throughout. The shelves are real flat, the lamp could use more detail as well.
There is quite some contrast in the final render, probably caused by the light with it’s sharp shadows. (probably direct sunlight?) Maybe you want to test with a bit more overcasting HDRI or softer shadows.
Is a collage an idea, like 3 pics in one?. That makes it more interesting. Will some text in one of the corners do something good? A subtile border an idea?
I agree with @SterlingRoth , the shelves could use more “dimension”. You could move the shelves (the horizontal pieces of wood) a bit to the back and maybe bevel the harsh edges. As for the lighting, it almost looks like there is an invisible lamp right next to the left sofa, the room is too bright.
I agree with the collage idea. Architectural renders are inherently intensely boring for everybody but the architect so those that pull it off work on the presentation. Frames, collages, insets, day/night, DOF, camera effects, dust particles in the air (I think that would work in this case), smoke from the coffee cups and perhaps hints at little stories with forgotten socks, shoes, toys, (underwear?). I like the dodecahedron even if it looks a bit distorted. They are a must in the modern household.
There’s a lot of clipping going through(which is not good for the viewers) or else perhaps you did that on the post processing.
Btw nice render though.