I've always been under the impression that adding split screen can limit how much is pushed in the single player mode. Is this not the case?
Not necessarily - split screen can start to turn off features and scale back various kinds of detail settings to reduce the workload. And most of the time the reduced screen resolution helps a lot to hide these handicaps.
If I had to compare H4 level design to any game it'd be Doom 3 instead. Lots of detail but kept at a low visual weight, lots of colored lighting to paint environments...
Not surprising considering Kenneth Scott's background.
UT is IMHO very different.
I understand it's silly to judge shaders and such from cortana, but wouldn't she be a good preview on the improvements to character art, more specifically the modeling?
Well the character's face is improved from Reach somewhat, but it's very hard to judge because Cortana is still somewhat stylized. The Elite and Chief are very heavily detailed but once again it's kept in nice artistic balance.
Will be interesting to see more of this game. I'm also a fan of Sparth's work (concept designer on Rage environments) and his Halo-themed art revealed so far is quite amazing - and a great challange for the 343 level builders...