Their art/model team is kinda amateur honestly. The eldar for example look awful. The chaos and eldar don't really look all that angry in their helmets. The dark reaper helmet especially looks like he's got a derpy smile. Nothing compared to how grim and solemn they look in the tabletop models. The texturing also isn't really there to give a lot of the armour some "depth" and "life" to it. But ya, that helmet looks dumb as all hell.