I have been playing Call of Duty 4: Modern Warfare for a few weeks now, and after the awesome single player campaign, I have devoted my time to the multi-player portion of the game. The MP is just fantastic in most aspects of Call of Duty, both visually and game play wise as well.
One of the features of the MP is the ranking system. You don't earn any Xbox Live achievements for multiplayer, but instead you earn your "ranks" through a point system. You acquire points by playing the game, finishing challenges, etc. Once you get to level 55 you have a choice of whether or not to enter Prestige Mode. In Prestige Mode you basically start all over from the beginning in the ranks and you can do this up to 10 times.
The odd thing is you really get nothing for doing this. The only obvious thing you get is a different insignia next to your name for each level you complete. No weapon unlocks, no special challenges, nothing else to speak of for completing the ranks again. A few days ago I had the choice to go into Prestige Mode and I went for it. As of today I am level 30 on my second time around, and I'm already tired of having to unlock all the weapons that I had previously done before. Opening everything the first time around was fun, and it's not too bad now, but I it's already getting annoying having to do this again, so hopefully at the end of this level I can just stay where I'm at, and play the game normally.