Yes, it’d also say scale is the biggest issue here. It sort of looks like a small toy, at least from the video. It needs more surface details. Adding more details with geometry is probably the best way to do it, but textures could also be improved. Huge objects needs huge textures with lots of details.
I would also increase the focal length of the camera. As I imagine it flying through space, a camera would probably not be able to get very close to it (danger of crashing?) so someone photographing it from a far distance (several kilometers away?) would have to zoom in quite a bit, or use a telephoto lens to be able to frame the photo correctly. So maybe go higher than 300mm? To the point where it almost becomes orthographic.
I’m guessing since you’ve been trying to render with Maya Software, you’re using a standard surface material like blinn or phong. Please don’t use these materials
They just won’t be able to give you realistic results. Use mia or mila materials. And get some good reflections onto those materials. Put a texture into the reflection-value and glossiness/roughness value, to make the surface look more uneven and less CG-perfect looking. If you look in your video around 0:31, the specular highlight on the sides are too perfect, and needs some breakup.
Don’t use ambient occlusion either. It’s basically a legacy technique that was used to fake global illumination before superior GI-techniques were invented/fast enough to render. Now it’s mostly useful for games and few other areas. Not something you want to use if the goal is realistic lighting. Use Final Gather instead when you’re rendering with MR. It will give you better results, and will also render A LOT faster if you have the right settings.
As for the lighting, I wouldn’t personally use a 3 point lighting for this kind of scene. I would only use it for portraits, interiors, product-shots and this kind of stuff. For renders in outer space, I would suggest only using a strong single directional light, to simulate a nearby sun/star. And maybe use a huge, blue, off-screen, planet-sized sphere nearby, to cast some indirect lighting onto the ship, to sort of simulate the ship orbiting a planet.
Not sure what exactly you are using the depth pass for, but I definitely wouldn’t use it to create depth of field in post. Any noticable depth of field would probably just make it look like a miniature model, in the same way the tilt-shift effect can make photographs/videos of huge cities look like toys.
These are all of course my suggestions, and you don’t have to follow all of them. It looks pretty awesome already. I would love to see an updated version of this some day 
