Levels determinate how powerful and skillful you are. They range from 1, which is the starting level, to a maximum of 100. Once you finish a Quest a moderator will read all your adventure and fairly administer experience points, the more you participate and the better you write the higher your loot and experience reward will be.
Depending on your Intelligence level you will gain a new perk after gaining a determinate amount of levels, the higher your INT the more frequently you will gain perks. More information
here.As your level increases so will your fame (or infamy). After reaching level 20 you will start being recognised and considered useful among the members of your own faction. Once you reach level 40 you will be famous and important among the members of your faction. Reaching level 70 will make you gain Hero status and will have a great amount of power inside your faction. Only the few ones who make into level 100 are considered Living Legends and might be given control of their Faction.
This fame will also make you gain the unwanted interest of the enemy factions. The more important and famous you are the more chances of having kill squads or a bounty placed for your head.