Nice Sergeant! I liek the armor (although it is a bit light for Ultras IMHO). The freeghand shading on the tabard looks odd for some reason. Good Purity Seals, neat script. Metallics (YA metallics!!) look spot on. The pose is cool (somebody has been envious of a Dire Avengers Exarch! lol)
I'm not sure about the hazard stripes on the guns, maybe a bit too orange for my tastes.
Everything is blended well and looks natural.
My only real gripe is the round thing on the base. I hate things hanging off of bases, it looks weird.
Great job overall!!