I know i'm late, and I know ADS is functionally the same in 5 as scoping in, but i'm still flabbergasted. For the record, I love halo, absolutely love it. I didn't even mind Halo 4, because I felt when 343 said "we've learned from Halo 4" they were, and probably still are, telling the truth.
ADS is the one, and only complete breaker for me, for a couple of reasons,
1, and most importantly, it's a blatant visual queue that Halo is still looking towards other FPS' for inspiration, instead of being developed on its on merits. Halo, to me, has never played in a way that I think accomodates it.
2, they're shitting over the rules of their established universe, seeing as Spartans specifically don't need to do traditional aiming down sights as weapon scopes are connected to their neural laces.
I'll get over it in time, but holy shit what a shock that was.