The model looks really nice and original, Also very covenant like, alot like the bus that is in halo 2 (I dont know if it is really called the bus) 7/10
Things that can be changed:
Ammount of overlapping polygons, there are alot of objects which collide with eachother, and that can make it look worse, Most people would use Boolean in this situation.
It looks like you mesh smoothed a few boxes, so that will cause alot of lag. Although you possibly chamfered the edges, or made a chamfer box, its always hard to tell.
honestly it looks like it has way too much firepower. and it looks like it would be tough to kill the driver. those two things combined makes it too appealing to vehicle whores.
i forgot to say that this is a well done model. but it needs to have less straight lines. all of the covenant vehicles are organic shapes.