Pros
You get regulars all the time. As time passes you begin to know peoples names and have full on conversations with them. This "Recognition" follows you outside of the workplace. I live near the Mace I work, so I see the regular customers all the time and always say hello. If you're part time like me, you'll also get those who'll be like "Haven't seen you in ages!". And it's nice to see those faces each time.
Cons
The work gets repetitive. Very repetitive. Sometimes there's no work to be done and there are times where you could be standing at the cashier desk with no customers.. and it gets boring. I think cashiers should be allowed a chair to sit on if there's no work to do, or if there's nobody in the shop. There's no reason to be making us stand for 8 hours a day while the management can sit upstairs.