Those are okay, lose the outlines, and add some finer details. Looks like it was made in paint, mind you, it looks good for being made in paint, but it still feels like it was made in paint. By adding finer details I mean sharper lines for the traveler's bottom, and the building need to be... better? I don't really know how to describe it. They need to be sharper, more detailed while still maintaining that silhouette feel. Get some inspiration/reference from the wallpaper Bungie has released.

Wow! Awesome!