OK, if you want I give you my unbiased opinion; I think your terrains are often a bit 'exxagerated', and not really 'natural'. Take it with a pinch of salt, mind you, I don't mean it negative, as I do like your cerativity in these planets. But I think if you make the terrains more credible and detailed, you win a lot of realism. The background also looks like a background and in this case isn't the highest resolution I think. You might consider a mix of background and atmospheric clouds.
I hope this helps, without meaning to offend.