As previously mentioned, I highly recommend lowering the stressful brightness of your buildings. Without having read the body of your post, I immediately thought that your build was a funhouse, not a city centre. Real cities have brick, metal, glass. You need only look at the images @Axcerious has posted above.
Subjectively, the fact that you have chosen for everything in the build to be plastic rather than exploring a variety of materials and/or decals, and trying to augment its realism, makes the whole thing look cheap. Instead of pure blue windows, use the glass material with dark marble behind it. To be a good builder, you need to think outside the box.
Generally, the place looks really abstract. On the second image, I’m confused what that small brown contraption is on the right. I also think it’s weird how the buildings have small, sporadic bricks of a highly strange colour. (e.g. The salmon-coloured building with bright red bricks). The exception to this, in my opinion, is your light pink building with white bricks. However, I would argue that making the bricks appear on the side of the building like this is sleeker and more realistic.
I am uncertain what these striped lines are on the edges of the pavement. I’m assuming it’s a cultural thing but I’ve never seen them before in real life. Why do they jut out from the pavement itself?
Anyway, I would recommend adding more detail to the pavements themselves. Right now, they are kind of just… silver bricks. That’s not what a pavement is. They should really be represented more realistically, made from several rounded bricks. Also consider the fact that road paint is necessary, i.e. double yellow lines at the edges of the road, white lines in the middle, zebra crossings. To give off a very realistic vibe, I would recommend curving the road ever so slightly and having drains in the edges.
In terms of building, you already expressed that you don’t class yourself as being as highly proficient as others may be. In light of that, I would only recommend that upon starting a new project, you highlight at the start what you want to do. For me, it is always “I want to build the most realistic place I can.” This ambition has led my building style to improve drastically over two years. The people who always maintain the same building style and never seek to improve do just that… not improve. Consider building to be less about producing something and more about proving something: proving a new idea, a new theory, a new style of building to be of merit and work.
I hope I could be of some help. Good luck with your build and all future builds.