Pros
Usually get 40 hours (or close to it), even if you're part time. Cheap health insurance (around $40 a month). Job security; the biggest way to get fired is by missing too many days. No matter how bad you suck or how useless you are on the job, as long as your attendance is 100%, you're golden.
Cons
Schedules get changed a LOT. Sometimes it will get changed two or three times a week, and if you overlook a change and miss a day, you will get marked as absent. Explaining what happened will not get the absence removed, only marked as "excused", which still counts toward your absence total. See the "only way to get fired" section previously mentioned. As a walmart employee, you will never hear the end of "people at walmart" jokes or references. Other cons include rude customers, but it's retail and that's to be expected anywhere. You are also expected to scan your namebadge on the computer every time you start a task, scan again when you're done, scan again when you start the next one, etc etc, so they can continuously monitor what you're doing. Luckily, some departments whose jobs are not so easily quantifiable are exempt from this... although I'm sure it'll be coming eventually.