not bad, but if i have a few small critques. I like the composition, but there a few things that stood out to me that i think you could fix. first off, the stars, they are way to dense for being a shot close to a planet. i would definatly try to slim out the stars by using levels or curves. next i would suggest you use the extract tool in photoshop and go around and get rid of the black around the c (it looks like you did this in more than 1 render or had the c from another render). and finally the lighting seems a bit off. the planets lighting seems to be coming more from the back, but the ships lighting is like directly from the left.... so it looks kinda off to me. anyways, sorry about the exceesivly long post, i do like the picture, just had some suggestions on it
hopes ya don't mind to much (or get pissed with me lol)
Robert