Like others already said, it's totally subjective. I've seen some Walmarts with pretty good fish and care, but I've also seen some pretty horrid ones. That said, I bought some of my fish from there, and even the neon tetras were very nice and healthy.
I had them for about a year until I decided they were eating too many of my shrimp but didn't want to move them to the other tank because the angel would eat them. Sold to the LFS since I've heard that Walmart will just flush any fish returned to them, alive or dead. I don't know if it's true, but I didn't want to take a chance.
I'm leery of buying from Walmart since I don't like their general policies and lack of care for the fish they carry, but even local small LFSs can be really bad too. Depending on the store, it may just be the best place in town. As long as the fish seem healthy, the tanks seem well maintained, and you don't plan on returning living fish to WM, I guess I would buy.