Im not so sure about overpowerd... They are obviously very different from the covenant but there are somethings that annoy the hell out of me. For example.. Hawks are amazing units vampires do own them yes and i think wolverines are pretty good agaisnt them but the rate you can spam them out is very fast quite overwhealming really.

Same thing goes to the vulture spam aswell.

EDIT - O yeah and gauss warthogs are OP aswell The gauss cannon itself is very powerful along with the grenadier in the front seat there excellent speed and mobility the fact that they are cheap as chips and their build time is very short.