Josh Holmes implies on Twitter that aiming still works more or less like what we're used to. Other leaked MP videos appear to confirm this, showing standard reticles and players making use of the AR, pistol, and what appears to be the SMG without zooming in. If ADS is aesthetic-only, I'm cool with that. After all, there's no way ADS would work in Halo except on a select few weapons. It'd be impossible with the AR, plasma rifle, Needler, and other weapons that lack sights or a scope. I guess we'll find out for sure tomorrow. Here's hoping for the best.
Also, I see that the health bar is back, so maybe health packs are back, too. I'd like that.