To know if your rendering is good or not, I need your answer to:
"What's your story?"
The values behind good rendering are not obvious. In determining whether a rendering is good, we need to know the story intended by the designer.
Do you feel your image describes an architectural space? Or not?
What effect on the design do these factors present:
Time of day?
Weather?
Wall color?
Texture of the space?
Let me list some ideas about what makes a rendering good:
1: It actually seems like a real space where light behaves with correct physics. Yours looks like an oversoft photo studio with magic lighting.
I dislike this approach, but if it is the way you want to tell your story, then okay.
2: The composition captures the eye. Once you look at the image, it directs and deflects your eye path to a circular entrancement where you become enamored and hypnotically sign the mortgage agreement. "Composition" is as important as materials and lighting. Even simple exposure tests should show the effort of composition. It is like when I did my first prison. I asked the boss "What's the design theme?" He said "Kid: Keep 'em in!"
3: The story. Entourage and lighting should create a specific mood. You think like an art director to establish mood. Our work is not just a bunch of stuff in space. It aligns with people's life concept and to make good illustrations the designer must deliver the expectation.
4: Finally: Does it make people say "Yes?" Does a lay person engage with it?
So, to address your "is rendering everything" question, my answer is "Yes, rendering IS everything as long as it authentically shows the ideas and spatial qualities of your real design."
The reason I say this: architecture IS primarily about what you see, and the feelings produced from sight. I don't know of many conscious efforts to make architecture an auditory experience, except that big halls should echo to create awe and concert halls need precise decay rates. And the sensual? Touchy velveteen and swede-een stuff stays in the boudoir. Mostly we make slick, easily cleaned surfaces.
It is all about "story."
Assignment to students: Read Robert McKee's excellent screenwriting book "Story." Then 1000 words on "How modern cinema affects design communication."
Dwight Atkinson