@Stilgar: I'll try to. Each character type that you play, like Diablo, has a certain set of combat abilities and magic unique to itself. Instead of skill/magic trees that progress by character level and path as in Diablo, the gaining of abilities and spells is totally open and caused by gaining a rune for that ability. A Seraphim character can gain the Heavenly Magic power Celestial Light by finding a Celestial Light rune in the game. After she gains the power by using the rune, each Celestial Light rune she uses thereafter will add another level to the power of Celestial Light, increasing the duration, damage, etc.
The character system features a set of skills and statistics which can have a direct (or indirect) effect upon the Combat Arts or Magic Skills of a character. The Seraphim's Mental Regeneration statistic, for example, affects how quickly her Heavenly Magic power Celestial Light regenerates after it is used. This statistic, along with others such as Strength, Endurance, Dexterity, etc, can be increased as the Seraphim goes up in level. Strength affects how much damage you inflict with close combat weapons, like swords or axes. Dexterity affects your accuracy with ranged weapons and the damage you inflict with them....and so on.
Add to this a set of skills you can gain and increase as you go up in level. Weapon Lore, for instance, will increase the damage you do with all weapons, close and ranged. Sword Lore increases your accuracy and speed with sword weapons. Ranged Weapons skill does the same for bows or crossbows you use. A Seraphim that invests heavily in her Mental Regeneration stat and Heavenly Magic skill, for example, will be able to use her Celestial Light power more often in combat. There are other powers, of course, but hopefully you get the idea.
There are also Combat Arts that rely on other stats and skills for their effectiveness. A whirling multi-hit attack, for example, does damage according to the weapon you are using, which is affected by your stats and skills.
Like Diablo, you can be as inventive as you want to be by developing builds, which I like a great deal. I prefer a Seraphim that is heavier on her Combat Arts than she is with Heavenly Magic, since the Seraphim is quick, and has nice combat moves. I like a Dark Elf that is blindingly fast and dual-wields.
Edit: Also, the world of Sacred is somewhat less linear, allowing you to roam freely wherever you wish (unless the completion of a certain quest prevents you from gaining access to a stronghold, like a Dwarven dam you have to disable in order to enter a Dark Elven fortress later in the game). Each area of the world becomes more increasingly difficult, and usually when your newbie character wanders into an area that is full of Sakkara priests and lesser demons, they'll let you know about it by saying something like "A strategic retreat might be called for here."

Still, it doesn't stop you from getting yourself slaughtered. It's your call.
