I hate to come off like a troll, but I had trouble really getting into Borderlands. The main problem, as I see it, was that I was playing it alone. But the idea of a game built around "go here, shoot this, pick up loot, level up, continue ad nauseum, restart New Game +" seems like a huge time sink with no real benefit. I can sink 50 hours into Fallout 3 or Final Fantasy ___ because there's a story attached with the monotony, but Borderlands seemed almost pointless and had a paper-thin story to drag you along. It doesn't help that the promise of "OMG UNIQUE LOOT" doesn't really do it for me, nor does a game with endlessly respawning enemies.
So yeah, count me out for the sequel.