From what I've seen, you still need Credits to rank up.

To reach the first rank, you need 750 XP/cR to rank up. There are some videos showing that.

Not sure about there being highest skill or not. There's probably a video on YouTube explaining that.

I heard that the ranking system will be similar to Reach (i.e if you play you rank up), which sucks. A ranking system like Halo 2 would have been nice.

It will be similar to Reach's but at the same time will be like a ranking system that we've never seen before in any halo game

Ive played the multilayer from the leaked copy, i can say that the ranks aren't like halo reach halo 3 or any other halo, it is basicly the same as call of duty, you start off at rank SR-1 and when you rank up you'll go to SR-2, SR-3 and so on, while playing multiplayer you also gain spartan points from ranking up which enable you to unlock weapons in which you can place into a load out ( create a class ) I hope this helps

magicbakes wrote Ive played the multilayer from the leaked copy, i can say that the ranks aren't like halo reach halo 3 or any other halo, it is basicly the same as call of duty, you start off at rank SR-1 and when you rank up you'll go to SR-2, SR-3 and so on, while playing multiplayer you also gain spartan points from ranking up which enable you to unlock weapons in which you can place into a load out ( create a class ) I hope this helps

Oh ok thanks for the info. I'm assuming SR stands for spartan rank. i cant wait for this game

There's a total of 130(SR-1 through SR-130) ranks. The first 50 ranks are basic ranks and then the last 80 are specialization ranks. There are 8 specializations each with 10 levels(These levels are like/as hard as levels SR-40 through SR-50).