Frank has once again hit the nail on the head.
Basically, our eye is usually drawn to the lightest part of the picture. If we compose and tone-map things effectively, we can make that work for us, but it does not do so here. We don't see the picture as a whole, just that little white cloud. Essentially, what you have is a sky shot with a strip of landscape at the bottom to anchor it. Any of us can do this, and it will end up looking much the same - and unless the cloudscape is really special (which this one is not), the picture will have little merit especially in portrait format. Conceived in landscape format it would have a somewhat better chance of success. I am sure that Karoo is a very special place, but I think that you could convey its essence much more effectively with a different approach.