The sentinel looks pretty cool, but maybe add some Halo-style flair - it looks like something from an anime series.
As for the scene, the thing it wants is detail. Trees, for a start. It looks like most of the terrain and sky were done only in Photoshop, in 2d. If you used a mesh for the terrain, it would look much better.
actually everything other than the explotion is in blender
i will be adding trees… a bunker… more sentinals… and be making the scene much larger… this was just a quick test of seeing if i could get the sentinal to look right in a scene
i have the sentinal pictured as described in the book… i cant really go and change from what was described… cause its a halo fourmn that im doing this for