Some things you left out

Forge

This is coming out separately around Christmas but it looks amazing and these "cartographers" will be able to do some crazy awesome things. Plus this will keep the new BreakOut game type fresh.

Speaking of awesome new game types. Warzone looks like it will be a ton of fun. This is the 12v12 plus AI gametype that utilizes the new Req system.

People are worried about Req cards and them giving people an un fair advantage but those people are stupid and haven't looked into it completely.

The weapons and vehicles you get through req packs can only be used in Warzone gametype, furthermore you have to perform well enough in each warzone game to gain access to certain weapons and vehicles thus keeping the gameplay fair.

Req packs will give you cosmetic cards that crossover into Arena but those are only armor and assassination animations.
heres a vid of a Warzone game that show how the req cards work and the awesomeness of 12v12 plus AI LINK

The campaign is also offering a lot of changes, with the two teams Osiris and Blue team having four members in each, when you play a multiplayer campaign with friends you actually pick who you play as and they all have different loadouts, for example linda starts with a sniper.
If you play a single player you play as locke or chief and you have the ability to somewhat control team members. Plus instead of dying I believe you get downed and have to wait to be revived, idk how I feel about this but it now makes Legendary co-op super hard because your friend can no longer die then you run back to give him an auto spawn you have to go fight and save his arse.

Im super excited for this campaign and I loved the story in Halo 4 but I hope they improve some of the gameplay.

Im so excited for this game is almost pathetic but like I said I think this will be one of the best halos, idk if I spend as much time on this as Halo3 but that's because im older and have a job now.

GT: Prubby