It's fine for me—though I probably fail the swipe-up gesture in one way or another 10% of the time, say by accidentally engaging the task switcher instead, or not quite getting close enough to the edge, which basically never happened with the button—but the button was a great affordance for the less-tech-savvy.

Swiping up with your thumb is pretty awkward though.

That's a good point. It doesn't feel good with the case on, and it makes me feel like I'm gonna drop the phone with the case off.