You have a good star, But for now - try to add size and details. Your buildings should all be the size of your twin tower's building or bigger, while holding tons of exterior and interior details. Your Burj Al Arab is very pretty, but it lacking interior and holds very small exterior details. Try to add more details around it so the floor around it isn't so empty. Your twin towers are very good and show potential, but they also lack interior and have little exterior.
You should also try different building styles, such as medieval. Building in multiple styles shows that you can tackle any type of building. Right now, your buildings are mostly modern skyscrapers.
You show potential, keep going! But for now - rejected.