Pros
Because of walmarts success, it draws really successful individuals. It is diverse and has an ability to stay focused on core business principles from top to bottom, while an ability to try new ideas to allow it to improve if these ideas are profitable and sustainable. If they are not, walmart has no problem with dropping the approach and reverting back to what works in a heart beat. The pay has evolved over time top to bottom, as with other peer companies, so that they may draw the talent. They have a 401K that the company matches up to a certain amount what you contribute. The bonus / stake holders programs have changed over time. There is a good open door policy. There is a lot of opportunity, depending on which way you want to go.
Cons
The frequency of new company programs seems to take up more time that allowed by schedule. Although some will say this is probablly a time management issue. Often times there is an over zealous nature that catches on with a can do attitude, where managers along the line of authority will commit to something without giving a lot of needed realistic feedback prior to starting a program. On the flipside, it is that nature that moves the company forward.