JPEG Jedi

Some thoughts:
The central structure (that recedes into 2pt) is softer than what you would see in reality while the blue building window lights in the lower right seem to be in crisp focus, I'd say more so even than the 6 pale greenish windows in the main structure in the mid/foreground.

The left side tends to go extremely dark and youwould expect to see more reflected light , although it could just be my monitor. The sky is a nice focal point. Perhaps limiting the number of plate photos or controlling their composition more from the start would be helpful.

I've heard it said that a key to good matte painting is closer to impressionist way of working, in that if you tighten up too much and overwork a particular area it feels forced and that it is better to give just the right amount of detail and let the mind of the viewer have some wiggle room to fill in the gaps. Not being a matte painter myself I am probably not qualifed to say for sure.

Obviously, check out artists in the business like Craig Mullins, and if he is still around, Peter 'Loki' Baustaedter. In general this is already better than much of what I've seen, and I'm really not interested in patting your ass in saying that.