Now i'm gonna say some stuff that a lot of people will hate but this is what I want so I don't care.
1. More scripted events – Now I'm not saying go crazy with it like Uncharted or COD, but the 10 second sequence in the beginning of the game was cool. It looked really nice and was almost impossible to fail, which I think is exactly what a scripted events should be. A couple more of these in the game would just add more variety to a game that already has a ton of it and thats not a bad thing. Also a turret sequence would be cool, like the one in Reach.
2. More Flying – Reach had a flying section that was quite good, now the flying section in Halo 4 was fucking awesome! It was pretty much the trench run from Star Wars I did it in one go without dying and it was the coolest moment in the game for me.
3. More music ques – Halo 4 seemed kind of light on the battle music compared to past Halo's, however I felt when the music did kick in, like the last mission while flying, and when Cortana is splitting her self up it was much more impactful than in the other games.
4. More Spartans – I'm tired of fighting beside weak ass soldiers, I want to start a level with me leading a charge with 15-20 Spartan-IV's behind me and just wrecking shop.
5. Boss Battles – Not like Tartarus from Halo 2, but more like the Scarab fights in Halo 3.
6. More Awe invoking landscape – The moment in Halo 4 where you walk through this grey/brown blown up environment, then see a little opening in a mountain side walk through it and are greeted by one of the most gorgeous vistas in VG I can remember was fucking awesome. I literally just stood there and stared at the environment for 5 minutes because the music and the scenery were just perfect.
7. Cities – If not on Earth let's go the the Elite homeworld and destroy it, because at this point fuck them.
I have some more but i just finished the game and this is what i thought of right away.