I actually quite like the dark face on the Universe version. It differentiates Starscream more from the other Seekers, matches the animation model better, and evokes the all-black face of the G1 toy. But then, I like Transformers with oddly-colored faces. The silver faces get booooooring. I think I may also be one of the few who likes blue-faced Ironhide and white-faced Silverstreak. Anyhow, that aside, I agree that the deco on Universe Starscream is bland and lacking in detail. I think it's his knees... those big, unpainted white squares on his knees just make him look unfinished. And I do like the airshow-inspired patterns on Classics Starscream, it was a different and fresh take on the character (not to mention it fit his showboating personality). I'll say this for Universe Starscream, though.... he's great for kitbashers looking to make more Seekers! That bone-white plastic is just begging to be dyed. I ordered two extras of this guy just to dye into other characters.
I think it's awesomely ironic that a lot of people that want the classic to be even more show accurate.... ...hate the fact that Hasbro just copied G1 Toon Starscream's paintjob from his model sheet directly to the toy. Ah, such irony.
The dark grey face is accurate to the animation model. Starscream's face is darker than that of Skywarp or Thundercracker. In addition to the previously mentioned all-black head on the G1 toy, the Marvel Comics incarnation also had a black or dark grey face.