* The coastal shape looks good to me, except it is visibly constrained by the size of the rectangle you started with. If you expanded the document size to include a whole lot of ocean around the edges, anybody could still guess with a high degree of accuracy how big the original document was, since on all sides you have land ending right on or close to the edge of your document.

* Is what you've shown the whole world?
If so, and it's supposed to be a round world, you'll generally want a surface 2X as wide as it is tall, so you can easily wrap in around a sphere.