You "hardcore" halo fans need to grow up.
First of all, the ADS mechanic is no different than that of older games, except now it looks different. It is just a different appearance than the zoom function. It does the EXACT SAME THING.
Second of all, sprint does nothing but add to the craziness that is halo multiplayer, it is not a huge game changing addition.
EDIT: It has come to my attention that sprint disables shield regen. Even better for you "hardcore" fans
EDIT 2: You can not aim while taking damage.
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ADS covers up like a fourth of your FOV.