I would say that everything you've put in the wall is executed perfectly.

The hills in the back are particularly effective and a style I've not seen before. Also the vector in the front is a very good job. The sun and the (I presume) hand made lens flare are also well executed in my opinion.

My only slight criticism would be that it lacks a sort of middle distance--you've got background and close foreground, but it sort of makes the foreground look like a flat layer. There's no sense of the grass 'stretching back into the distance'. But that's a relatively minor thing that doesn't 'break' the wall for its absence.