Experience is simplified. They give you 1 XP for every scenario, and when you've been given 3 XP you advance a level. What's more interesting is a mechanic called Prestige Awards that represent your reputation in the Pathfinder Society and your status in the sense of stature within the group. It's not immediately clear if there is a difference how this reflects between your faction (you must pick one to participate) and the society overall.
The factions are maybe the most interesting part of the society play. You pick your faction at character creation. It might affect the character type you play, as the factions lean different ways or focus on different things, but it doesn't affect race or much else mechanically. The Pathfinder Society as laid out seems very much like Star Trek's Federation, if the Federation had groups with different goals who are trying to get a leg up on the competition, working together for convenience and benefit only until such time as there is a great enough opening to gain power.
There are five factions each with their own view of the world and way of approaching things. Each scenario in the year contains two missions for each faction that must be quite intertwined given these scenarios are meant for 4 hour convention games. It's really fascinating to consider the plots and subplots that can be involved in the machinations of these factions. I'd really like to see how things play out considering that the faction missions--sub-agendas--are ultimately meant to be completed; both tied to and separate from the main adventure plot. The final result, a push and pull of power, the fallout of such results, the possibilities for the future, it's just way too exciting.
It must be amazing to see how it all falls in place. Perhaps amazing enough someone should chronicle them--say as novels. Not that I'd want to undertake such a Herculean task, especially as someone sitting on the outside of it all, meaning not one of the scenario writing staff.
I'm reading the Guide to Pathfinder Society Organised Play 2.0.
The core book of the game, and other books for it are found at...
http://paizo.com/pathfinderRPG
Pathfinder began as an offshoot of D&D 3.5, but is now its own system, something almost of a D&D3.75 with its own unique setting. The Organised Play system allows for characters built to specification to be played in any tournament game, or official Pathfinder game. Each year specific adventure modules are released that form the official stories of the society.
It might be something akin to Living Greyhawk, though I'm not entirely sure given I've never been involved in a living campaign. I'm interested in reading about because it is a fascinating idea having a game with a timeline that people can follow that is added to continually. Nothing stops you from playing at your own pace, or skipping bits, or playing your own adventures, but it must be rewarding for those involved.
If you know more about the Pathfinder Society and what it's like to be a part of it, or have played in a living campaign, drop me a comment.
Robert G. Male