Sacred 2: Fallen Angel Preview had the chance to check out a recent build of Sacred 2: Fallen Angel and have whipped up a short preview based on what they saw.
The monster AI adjusts its aggression levels based upon character and party size, but not by scaling the difficulty of the monster. It uniquely adjusts the group size of the attacking mob until the fight becomes even. If you are of no consequence, you will be left alone; if you are too powerful, the mob will wait until it can gather additional creatures before attacking.

With drop-in/out multiplayer and character saves as opposed to world saves, the gameplay is endless. Advancement in single player mode will not affect the story line in multi-player as the mobs adjust to both party size and level, not just size alone. Character saves that are independent of the status of the world (and quests completed) allow any two or more players (depending upon the platform) to simply pick up and go.