Recs.
Updated
Diablo III is an action RPG that supports 1-4 players online and locally. A hack 'n slash title that focuses on loot and heavy customizations.
SpecsUpdate
Pros
Pro Heavily focused around customization
About 30 activated skills per class, 5 unique runes per activated ability that modify how it behaves, and randomized gear that can further change how your character plays.
Your playstyle might dramatically change based off of how you want to cater to your team, what abilities you might have just unlocked, and whether or not you want your goblins fried or diced.
Cons
Con Less focused around growth than previous installments
Previous Diablo games were known for having permanent improvements throughout the game, where Diablo 3 focuses more on customization as you increase in levels rather than improving your abilities. There's a chance that you will unlock your favorite ability at level 5 (I'm looking at you, Rapid Fire) and never use anything else in the game, because you can. Many people consider this an issue with Diablo 3, and expected more of the "specialist" style of gameplay.