I will say this. Yes, they pay low wages. Yes its a burn out. IT for retail, is *generally* very high stress for penny-pinching companys. I would rather have that stress working for a dominant company than say for K-mart.
But yes they have a great can-do, really make it work attitude and if you implement something for wal*mart and it works, it will probably work anywhere. I know several folks whose careers were made at wal*mart. Almost any competitor will gladly snap you up with a big, big raise if you have made your credentials in wal*mart IT.
Oh yeah, and did anyone mention how nasty wal*mart can be if they find out you plan to leave them? (* if you quit and you are useful they figure you are going to a competitor *eventually* So therefore you are a "traitor" *) Most folks who quit try to leave as quietly as possible. Its the only place I ever worked where I saw that sort of behavior.