The only problem I see is that the purple pillar is not centered in the middle of the tower. It's a bit too foward. Otherwise, I like the cartoony feel and textures.

Something about the angle makes this feel very confusing to me. The thinner part of the tower should have a shadow close to the top as to give the impression that the top is actually resting on top of it. I also think the clouds should either encompass a lot more of the image, or that the perspective should be switched to iso in order to make it work.

Well done!