Gearbox Software has confirmed that Borderlands 2 campaign length is 58 hours long. Wait there's more, this run time is with respect to one of the game's five different character classes.
Steve Gibson said, "What we like to think about it is, Borderlands is a hobby. Some guide guys just did a playthrough of Borderlands 2 and they reported back to us that it takes 58 hours to play through the campaign – and that’s just one playthrough with one character,"
"So the depth with which people can get into that…Yeah we look at it as a hobby, and that isn’t even counting the new Badass Points system and how that’ll affect every character you do. We want it to feel like you get more for your money, we’re happy for people to pay their money once and feel that they get ongoing value."
Steve Gibson further explained why development team drop Arean mode from Borderlands 2.
"It was hardly used, so what we invested in instead was the co-op stuff. The Badass Ranking System is kind of a measure stick which says, ‘Look how awesome I’m doing in this world.’ So what we’ve invested in rather than Arena stuff is drop-in/drop-out split-screen co-op, and being able to re-adjust your questline a little bit to match up with other players."