As an auto box, there's nothing wrong with it at all. But neither the box itself nor the software running it is up to scratch if you're looking for a good 'manual mode'. It's still a case of buying an auto of you want an auto or a manual if you want a manual.
The idea behind paddle shifts is for fast, accurate gear changes whilst being able to keep both hands on the wheel. For that you need something in the vicinity of porche's PDK box. Even the DSG Volkswagen use is ok (ie mk 6 golf... The mk5 not so much) but unfortunately the commodore auto is a dedicated self-shifter with a bit of a suggestion box for the manual option. To be effective, the gearbox needs to almost pre-empt when you're going to pull one of the paddles and swap cogs immediately rather than waiting until it's ready. The whole idea is to put you in charge, otherwise what's the point?
Arguably, I'm taking things here to the Nth degree... But it's just my opinion.