Several, in fact
In this nearly 15-minute demonstration of Borderlands: The Pre-Sequel at E3, 2K and Gearbox show off how the game's oxygen mechanic works. Running low? Replenishment is just a geyser or maybe an enemy away.
The downside to The Pre-Sequel's lack of air is the constant need to keep your supply full. The upside is the incredible verticality it adds. Platforming in Borderlands has never looked so fun.
As an added bonus, we get to see what one of Wilhelm's capstone abilities is. Called the Vengeance Cannon, it activates a laser beam-shooting artillery once your health drops below a certain threshold. Unfortunately, it's never used in the video, but it sounds like it would just absolutely wreck everyone around.