Some tips,It looks very cartoony. Try adding pillars or other supports. (Ignore this I didn't see the pillars.) Also, don't make literally EVERY SINGLE WALL just windows. It isn't very creative. I wouldn't suggest making it in a square shape, uneven shapes or wedges in the building can make it look much more creative. see: http://www.sjphoto.com/hk-web/images/HK-skyscraper.jpgIt's very pretty over all.
This sky scraper looks very similar to the sears tower in Chicago.
A suggestion for your next tower is to make each floor thicker than 1 plate
Can I have a floor please.make it have pls