From what I read about user's impression of the 2016 Volt, people loved the L mode, while reviews of the paddle was more mixed (part of the problem is the Volt's is on/off with nothing in between). I guess the Bolt addresses that (it varies, not just on/off). However, it's not one pedal if it requires continuous pressing of a separate paddle (out of the modes listed only L-mode with no paddle can be considered one pedal driving; D may be too weak to qualify). Whether you like one pedal largely depends on personal preferences (some people are good at modulating the pedal and find it easy to put it in "coast" or any other regen position; while others have a hard time modulating the pedal and rather have regen on brakes or controlled separately).
Love the paddle on the Volt. If I want modulated regen, that's what the 'brake' pedal on the floor does. In urban settings, it's Sport, L, and I use the paddle. I seldom have to touch the brakes. Probably because I don't tailgate, I look far ahead, and I don't race towards stoplights that are red. And I still get to my destination quicker than most folk.