The pay I got was awful, awful, awful and my job was essentially picking up shoes for six hours. I would never work in Primark again - it really was a horrible place to work. The managers basically bullied me into doing overtime, and would often keep me up to an hour past my contracted hours without asking me - basically I had to - and later found out I wasn't even paid for this.
I'm not saying your experience will be anything like mine but on the whole I've learnt it's not a very nice place to work, and certainly not for the money you get.