Not more KILL medal or ASSIST medal. I do not like this for ASSIST's atleast, as i don't know if someone is dead. The kill feed could be from someone else. Some indication that the guy you just worked on is dead is helpful. Unsure how to fix, but Assist medal should be back.

Same with some power weapons. Railgun kill medal is not there (that one is at IGN, http://www.ign.com/videos/2015/09/25/halo-5-arena-multiplayer-commentary-ctf-on-fathom?utm_source=IGN%20hub%20page&utm_medium=IGN%20(front%20page)&utm_content=15&utm_campaign=Blogroll)

Promethean grenade has changed. Looks more like a Destiny grenade the hunters have that just drops a few floating items that sit there and wait. But there is a cool animation when it first explodes that "sucks you into a black hole" kind of effect. Really like that. Do not like that a grenade type changes functionality between games (hopefully it's called something different).

They have maps with 3 grenade types on it! yes thank you. I always hated that the sandbox felt limited per map.

Breakout changes with a flag in the middle. Seems to require a bit more damage now. Bigger maps it seems, and can change the color of the edges (from the original Yellow we saw to green and red here). Even has some power weapons.