Pros
In my experience, it was usually busy and I could rely on my coworkers. Every store manager I worked with was competent, and would put in well over the amount of work they should have had to. I knew that if something went wrong my my manager would be able to back me. The work is usually pretty easy, once I'd been there for a while and got used to the pace I could generally mentally check out while I was working.
Cons
The biggest con of working at Dollar General, at least for me, was the customers. While the majority of people are just trying to shop, the exceptions generally manage to be overwhelmingly unpleasant. Another con could be the pace, which while dependent on where you are located, could get extremely unpleasant during certain times, such as holidays or during panics. If you are bad at dealing with people I can't recommend this job, as well as if you have anger problems.