You're effectively paying a somewhat high interest rate. From the looks of it CBA's low interest card would be comparable or cheaper if you were young and held a bit of rolling debt. And right now they have 15 months interest free on their 'low' rate card.
I think the difference that's better for afterpay customers is being able to have your purchase chunked into installments, effectively making it more like lay by.
Also, cba should have made it black so it didn't look you were holding a learners plate credit card.
Our Australian banks are lazy.