Pros
Upon entering Prestige Mode, players unlock new icons next to their names. Higher levels of Prestige are usually indicative of more game experience. Players will usually get better each time they Prestige, but that does not mean that higher Prestige players are necessarily better.
Cons
Prestige Mode causes a player to lose all unlocked weapons and perks, and camoflauges. There are no Xbox Live achievements or PSN trophies associated with online play or Prestige Mode. -Wiki