Pros
A great reason to work at Wal-Mart is the fact that virtually anyone can get a job there doing something. If you have little experience/education it's a great place to start. If you work hard, there is a good chance that you can work your way into management. The compensation is OK for what the job asks for, though some positions that require more responsibilities offer little gains in pay over something like a cashier (ex. would be a Customer Service Manager). The skills I've learned from working there I feel I will take with me the rest of my life. Working for Wal-Mart is a very good first job for someone just entering the workforce as you gain valuable experience working with people (if that's your thing).
Cons
One of the downsides of working at Wal-Mart is also one of its perks. The fact that they hire almost anyone can be very frustrating. Working with people that, I'm sad to say, are unable to even read can be very frustrating when trying to communicate. Some people that are hired can also be some of the flakiest people, hardly ever showing up for work. Wal-Mart's attendance policy is very loose and someone can miss quite a few days before they are even considered for termination. Also, some supervisors that are supposed to be knowledgeable about what they are supervising constantly ask their subordinates what to do, and show that they do not deserve their position at times.