It is otherwise so good-looking that the HTL models start looking low-poly. :
...if the slight softness of the image is not intentional, that is.
Here's what I would do:
-almost completely dark sky would float my boat better - just a bit of nebulae colour here and there; not too much. I much prefer dark space bakcgrounds myself.
- put more contrast to objects lightened by local light sources. Almost completely black shadow sides FTW (IMO). And if you want to have ambient light illuminating the shadow sides of the objects, please make that light the same tone that the background average value is - ie. if you have that much red nebulae, the ambient should be red.
My comment is physically oriented; I'm a realism whore, what can you do. Aesthetically, I would also perhaps group the Medusae a little differently, but that's your choice obviously. I would put them first in classic FS diamond formation, then alter the directions of them a little bit (if, for example, one of them needed to evade an asteroid) and shake the formation a bit loose. Now, it looks a bit too loose formation to me; it would be better suired if they were fighters or assault fighters instead of bombers. Bombers should give an impression of steady progress to target, while fighters could be expected to maneuver more like the Medusae in the render.
The amount of asteroids could also be either reduced, OR alternatively alter the background to give impression of being inside a gas giant's rim or something like that... because that's the only place in space that can be even scarcely imagined to be that dense in amount of stones.
It doesn't suck.
And, as is obvious, these are my opinions of these pictures as just pictures. I don't know anything about rendering as a technique to make pictures.
