hard for me to put one answer...
As for my title above, it would depend on whether you are a beginner or more experienced , for a beginner then I'm am very impressed, and I can see the vast potential so long as you keep at it, if you are more experienced then depending on just how experienced, I might say that I would've expected a little better. But non of that will help you to get any better. whatever your level I'm giving you an 8, for a great start. Now I am a advent Maya user, but I have used other programs, and so I know that all the 3D programs, are general similar, even with all their respective differences. So I will be making my points from a Maya technical perspective, thought I assume that C4D wouldn't be to far off.
The first thing, and yes this has been said, it is too clean, all of your edges are to straight, if you were to smooth the ledges and concrete blocks that divide the brick it will at least round off the edges/corners, if doing that makes them TO round you can add edge loops near the edges of the poly cubes, this will sharpen the edges, the closer you put the new edge loop to the existing edge the sharper your smoothed edge will be, so don't put them too close or it will defeat the purpose.
A normal map on the bricks would be excellent to make them appear weathered, but at the very least, use the brick wall image (as a black & white image) and use it as a bump map so that the bricks protrude out further then the mortar
on all you metal, if you were to dial down the eccentricity/specular roll off, and even reflectivity to give a real, aged look right now everything looks like its covered in chrome
Get some reference images next time you model something like this, it will help you to go beyond just simple shapes with a texture on them
And for the last thing would be it needs to be less..similar, I know you duplicated and translated a lot of these elements in the piece and I know that was the point, but for it to seam "real" it needs to be more random. I noticed that some windows had a single vertical beam in the middle and a few others had cross beams and that a start, but also try having a few windows open, half open, a pane or two with a broken or cracked piece or glass, anything to "randomize" the image
So sorry to write so much but I always enjoy offering my opinions about 3D work, I always just wanna help others improve, in anyway I can, hoping they will one day return the favor :)
Hope you found this at all helpful