This is about the apparent feature of unlocking "upgrades" the more you progress in multiplayer.
I CANNOT STAND this concept. One of the biggest reasons I fell in love with halo as a multiplayer game was the fact that I could be a rank 1 and and be on a level playing field with a max-ranked player.
Lets make a hypothetical situation to get my point across more clearly. We have two people, each with the same hardware, internet connection, and skill level. They both play 100 matches 1 on 1. Ideally, each player would win 50 matches and lose 50 matches, since they are evenly matched. Now lets take the same scenario, but give player 2 the advantage of better starting equipment choices. The win/loss will no longer be even, because despite the fact that both players are of equal skill, one has the advantage of better equipment. Obviously.
I'm all for unlocking stuff...that's cool. But don't let it affect gameplay. It's one of my main gripes with games these days. Or at least don't make it multiplayer exclusive. Give me the opportunity to unlock these extra abilities/equipment through the campaign or something. An example is Battlefield 3. I started its multiplayer late, so aircraft were virtually useless unless I wanted to be stubborn...you see, you didn't start out with countermeasures, or even missiles when piloting a jet or helicopter. So by starting late, when so many people HAVE unlocked these features, i'm at a significant disadvantage against an opponent...even if I may actually be "better" than him/her.