I haven’t really followed Halo 5 News until recently, so I’m sorry if this question’s been asked already.
For the ADS feature, how does ADS change your weapon accuracy?
Is it actually like in COD where it decreases weapon spread and make your shots more accurate?
Or is it just a novelty feature or similiar the ADS in ARMA where it basically doesn’t improve the weapon’s accuracy and is just there just zooming in purposes?
It works the same way as zoom did for the most part.
It’s pretty much just a new animation for it. There are no penalties for using it nor are there any advantages.
ADS doesn’t provide any enhancement to aim or anything of the source
Its just a visual change but youll notice that alot of people will try to say its gamebreaking 
ADS tightens bullet spread for automatics, and may show an extremely minimal spread difference for precision weapons (likely not enough to matter). There is no movement penalty while using ADS, so you’re able to maintain an effective strafe if need be.
It’s the same as zoom in the other Halo games.
OK, awesome! It seems like my fear has been alleviated. Alright, thanks everybody for answering my question! 