All in All halo 4 sound like it will be good, i think they really they need to make some new play lists for Multiplayer, make them a little more competitive, things like infection, grifball, and slayer games like swat, these i think could be improved, the ranking system from halo reach i think should be kept as it was easier to understand and the ranks and i really think DLC map packs could be cheaper to get in MS points. Campaign needs to be more like halo 3 Campaign, staked with action and longer mission, but keeping most of the vehicle designies from reach as they were awesome, this also goes for online. In my opinion halo 3, halo reach and halo 4 as the best games about of the halo trilogy. I really that halo 4 is not the end of halo, and that there will be a halo 5 or something like that. HALO RULES :) :P
Halo 4 needs to implement replay value. Halo 2 didn't have much in terms of unlockables but having a 1 to 50 rank gave me reason (and risk) to playing online. Each ranked match was worth something to my rank. I don't care about playing a million games to get a master chief helmet. If they can bring back the ranks I think this will instantly become a hit.
Oh yah, I also forgot to say that they NEED to keep "hit scan." I will be really disappointed if they go back to Halo 3 (leading your shots). Realistic as it may be, we need to understand that half of the community plays on a crappy connection so unless they are going to dedicated servers, hit scan is a must. I also think the ability to search for custom games would be a huge hit.
I like multiplayer to have competitive gameplay, but my God they need to do away with soulless, perfectly symmetric maps. There have been some fun symmetric maps (the Pit, Sanctuary), but for the most part they are so boring. I'm not sure why some people automatically praise any map that is symmetric. Countdown and Zealot are horrific. Lots of tight corridors and corners to camp around. They need to go back to making fun maps first, like from Halo 1-2 and somewhat 3. I know Zanzibar is slightly unbalanced, I just don't care. We need more Lockouts, Headlongs, Turfs, Terminals, High Grounds, and Valhallas. This is why most of Halo's fanbase (including myself) play less or not at all. Reach has almost no fun, interesting levels.
Also, no more abilities, including sprint/evade. I'm so sick of playing levels where I get in a fight only to have the guy run away before I can kill him. And because of so many levels with tight corridors, he usually succeeds. In Halos 1-3, you could try to run away, but since I could chase players AND shoot at the same time, running was not a viable strategy. In Reach, if I want to chase after someone, I have to sprint. That means I can't shoot and their shields have time to recharge.
Here's why Reach sucks: Playing on levels like Countdown usually amounts to my enemy camping around a corner, throwing a grenade, firing off a few shotgun blasts, and then running away into a new corner and starting over. Even when I win, it is more of a chore than a fun game. --- http://26.media.tumblr.com/tumblr_lh7rekuKQR1qdtbqko1_500.gif
If we're talking about copys sold, then it just needs to have the word HALO in it. If we're talking about critical success, it has to do what Reach was trying to do ( and almost got). They have to keep the classic Halo formula, while adding new, quality additions to the game.
good solid story mode. really dive into the books.
its master chief. duel wielding must return.
create a spartan must return also where is create an elite??? also elites and spartans need to fight each other freely in multiplayer making teams of only one or the other in invasion game types only or perhaps others but you get the point.
i think a combo of armor abilities and pick up items(like drain shield etc) needs to be added. armor lock for instance as a pick up one time use item would be fine and balanced. but things like hologram,sprint and jetpack as abilities work just fine and are trade offs with equal balance and power.
also bubble shield armor abilitiy could be different from bubble shield pick up item. as it stands now the pick up item is indestructable and doesnt heal you the other is destroyable and heals you.
finnally....im not a multiplayer fan really. but the maps. good gosh the maps are terrible in reach. the firefight maps are also poor compared to ODST. seriously....better freakin maps.