While I appreciate your opinion, I have to take into account that the game has not been released or played yet by any members of the public. See, I'm being nice because what I was GOING to say is
"Halo 4 will ruin Halo, No one will play it, the Y2K bug will destroy everything, the world will end in 2012, Clinton will destroy America, Bush will destory America, California is going to sink into the ocean in 2005, Facebook is going to start charging it's members in March of 2011, and Perfect Black is going to be a Halo Killer."
See, everything listed above are theories. Actually, wild assumptions based on enough evidence to make a wild assumption. I get what you are saying, I really do, but frankly, I'm tired of hearing it. I'd argue with you using some of the information that's been released, but if previous experiences with this sort of thing have taught me anything it's that you will completely ignore all of it. Also, being a "true" Halo fan is a MASSIVE amount of opinion. In my opinion, you can't be a "true" Halo fan unless you love everything about Halo. This includes, but is not limited to, every single matchmaking gametype, the story (books included), the weapons, the armor, the characters, and everything else that has been in Halo. You, good sir, seem to be a fan of the multiplayer. Otherwise you would be bloody thrilled that master chief is making a come-back, and wouldn't really care about what they are going to do with multiplayer.
The fact is Halo 4 is going to be different. Of course it is. New people are playing, new people are getting good at it, new technology is coming out, and new competitors are on the market. If Halo released the same game over and over with better graphics and newer weapons, it would be the definition of COD. You cannot name a single Halo game that was the exact same as the previous one, or even one so similar that you could go from one to another without having to learn new things. THAT is Halo. If Halo doesn't evolve, it will get left behind and die. And all we will be left with is COD and BF. What you are asking for is for Halo to commit suicide.
As far as borrowing some ideas from COD, well why not? COD borrowed ideas from Halo to make their games better, so why can't Halo do the same? Don't judge a game that has given you so many hours of entertainment before you play it, or before it's even finished. This is 343i's first Halo game, but many of the 343i employees have worked on other Halo games. They aren't newbs. They KNOW what they are doing, and if you are a true Halo fan then when they ask you for your trust (which Frank has quite a few times) then you would give it.
/rant