Alright lets walk this dangerous tightrope together here. So the immediate reaction to this statement is that the game will be pay-to-win, and to be honest its not 100% clear if there will be some aspects that might be pay-to-win.
What is known right now is that you'll be able to use real money to have special skins for your Spartans. There's also talk of weapons and vehicles, though it is unclear if these items will give you a tactical advantage or not. What I can tell you is that people shouldn't be up in arms about this, at least not for the time being, this is literally DLC without putting it into the XBOX Live store.
Now of course there is a progression system in place to get you in game currency that you can purchase some of these skins and whatnot, so there might just be a group of gamers that start waving their fists in the air saying how its unfair that other Spartans get to look cooler than others.
All I'm saying is that if this does indeed only entail cosmetic changes to the game, I'm totally down for that. If there's some sort of VIP league or mode that requires some money up front, sure that's fine. The thing is if this is a spend more money on the game so you can actually play it after dropping money on the game, just to play, then we have a problem, and it's a big one.
Oh and here's a bonus piece, the E3 Gameplay Trailer: