Hey man cool stuff.
Now that i got that out of the way time for a critique. I think you should draw from life and do alittle realism with you drawings. That will help you in understanding how things are percieved in 3d form. Then you can take the lessons from lighting, tonal values, shape, form, even composition and apply them to your digital works that are not realism. This will benefit you and any artist alot. I personally think all artists of any skill caliber should do still lifes at least once a week for practice.
I noticed in some of your scenerary you have some unnatural linework in your rooms. One of your rooms looked as if it was in outer space (if that was intended good job) because it was tilted. While another room you had drawn it wrapped in a cuve around a wall. Your curve wasn't in its correct perspective and looked like it was elevated instead of flat.
These are all things you learn from darwing in life. When you draw in life and not from photos more often you will begin to recognize these misstakes and correct them. Also, even if you photo copy a photo perfectly there is still a chance that it will come out looking disporptionate or skewed. YOu need to have a strong understanding of life drawing while you work with photos in order to produce something that is believable.
Hope that was helpful, keep drawing you have some cool stuff.