Expanding on their video interview on Diablo III's PvP, G4 TV offers their own writeup to share their impressions of player versus player gameplay in the upcoming title.
So what is it? Arena is a place where you can battle other players without consequences. Your corpse won't get looted, and you won't drop a level. Developer Jason Bender said they may be supporting leaderboards and other ways to rank players in the Arena, but you won't be heading in there to find epic trinkets. "We don't want this to be the way you get loot," Bender said. In fact, the only real consequence of Arena is the hardcore mode, where if you fall in battle . your character gets erased forever. It's pretty much just for bragging rights, but Bender said they may explore some way to entire players into Hardcore Arena battles. With Battle.net and their love of decals, I imagine that's where something will appear.
So instead of having your fellow players turn into loot pinatas, you're squaring off strictly to win or lose. We battled 3 on 3 (thankfully, since I was the only non-dev) with every class except the Demon Hunter and the Monk. The Demon Hunter was only just announced at BlizzCon, so she wasn't in the same build we played, and the Monk was being retooled. Instead we all took turns with the Barbarian, Witch Doctor, and Wizard. Because I usually like getting up in the grill and playing smashmouth PvP, I picked a Barbarian. Then I quickly died, over and over.