...I think the main issue is the colour. Look at the first image, the planet has a mixture of dark and light areas, which is realistic looking at planets/moons of our own solar system. These need to come back as at the moment a lot of the planets are a solid colour with very little variation...
This very much so, you can still see massive variations in surface colour on the non land-able planets; particularly the volcanic types.
It would also be great to see more variety in surface scatter, i.e. large rocky outcrops and overhangs etc.