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Hiya! This kind of post would be best suited for the Smeargle's Studio General Art Thread, where you'll get a much better critique than you would with your own thread.
It looks pretty good though! I am not very experienced in banner making, but you use fading effects very well. My only qualm is that the black logo on the top, left corner of the building is sharp and clean in comparison to the rest of the banner. Perhaps you could put some opacity on that as well? Just a thought!