For indoor scenes you're going to need a good understanding of perspective so that squarish objects are nicely aligned. I think that's why the desk and bookcase look strangely-shaped. The bookcase, for instance:
- has shelves that appear wider in back than in front
- the shelf guards (? the thing in front of the shelf) "shrink" at different rates as they recede
... the mat has a strange shape too. I think all these problems would be fixed with proper perspective (1-point perspective in this case).
The walls close to the camera look too tall too (maybe it's a tall room though, I dunno :-) )
What would probably help is drawing the image out on paper first, take a photo of it, and then use that as a tracing guide in SCI Companion. I always draw the scene several times on paper first until it looks like I want.
Your outside scene looks a lot better (especially the bushes are nice), probably because perspective doesn't matter as much with more organic things like plants. But... there are still some obvious issues:
- The sidewalk chunks are different widths
- The yellow road paint doesn't use perspective lines like the sidewalk chunks do
- The sewer... is that supposed to be a sewer? I'm not sure what you're going for there.
The grass in the cracks is a nice touch.