Pros
As a uni student on a 12-hour contract, this has been a good job. Pay's fine, 15% employee discount is fine, other employees and management are fine. I worked in a smaller store and the regular customers were probably the best part - never had any trouble, even in a 'rough' area, and always had people asking after/looking out for you.
Cons
Usually short-staffed in some way (e.g. two-man cover for a delivery) which can make things stressful (if you let it). Hours were often restricted to contract, so if you wanted more you'd either have to pick up hours in a different shop or look elsewhere. Working with other uni students/people not in the job for the 'long haul' (in my experience) meant that some people didn't care enough to do their job properly which could mean more work for you.