Though some of the visuals and gameplay additions at first glance raise an eyebrow for me, some thoughts:
-if ADS does in fact function uniquely in that it's basically just a cosmetic zoom, I'm all for it as I think based on those videos, it makes Halo look far more immersive. If there's movement penalty, or hip-fire headshots won't be possible, I'm going to be super bummed -- as I've always leaned away from CoD and Battlefield for ADS being so mandatory and pace-breaking. But I don't mind the bottom bit of the screen being covered by the gun at all, it's the least important visual area, and based on the clips, does a lot to modernize the look of the shooting.
-Don't mind sprint. I'll always love Halo 1-3 for their sprint-less nature, but sprint in Halo 4 was the least egregious thing it did, and in my opinion, made large maps much more tolerable. Halo 4's biggest MP fuckup was always the perks, ordinance drops, and above all: completely abandoning weapon-location-based map control which was always a staple of the series.
-The screens look fine, I'm neither wowed nor disappointed -- it does seem to visually veer a little close to Halo 4 from an art standpoint (maybe due to placeholder assets since it's so far off from release). But based on the blurry clips, it looked gorgeous, so I'm hopeful. We'll see soon enough.