its not that your model isn't good mate. things to work on and keep in mind at all times:
First, greeble logically. Think about the object you're modeling. If its a fighter, then it will not have all of these really high raised panels, or a lot of protrusions jutting up and out. The idea in designing and modeling a sci-fi fighter is to make it believable. how is this acheived? well, its acheived through incorporating a LOT of elements of real aircraft and aircraft design. study the hell out of some airplanes, and really focus on applying that to your work. also, if you're trying to re-create something, go for accuracy, don't add things which aren't there. generally (and really true for WC ships) if you model them exactly, the detail is there. they did a great job in designing. i mean, look at any modern aircraft. the panel lines are very very small, and have nearly no height. everything is flush, its that aerodynamic deal. granted, theres no wind in space. but the look has to be there in order for your audience to believe it.
Second, don't down yourself, think 'okay. i know now what it is i have to do', and do it. you have potential out the wazoo man. keep your chin up, and apply things. when people comment on what does and does not look realistic, or accurate, or proper, don't keep doing the same thing over and over again.
Now, my final thing. And its the key thing I harp on the most...which is why i'm re-iterating it here. Model Accurately. Don't shrug off blue prints, or say 'well, it looks wierd here'. don't second guess a design. they don't change stuff from point a to point b. its the same model. the shot i'm posting up here will prove this to you, and everyone else. that's the top of the ship looking into the cockpit. anyway, keep your chin up mate. and seriously keep all of this in mind, and apply it. turn that potential full force into cranking out insanely high res models!
Brad Mick