OK, I'll be the odd man out, :-D
Is it worth it?, maybe. We've had memberships in sams, bj,s, and now Costco, Here, I feel costco is better, but if we had a super Walmart, I'd probably drop Costco. Our regular Walmart is where we get all paper goods, cleaning supplies, canned goods, etc. Costco has the meats, but supermarkets have the better sales on meats if you hit them right, you can't beat costco for chicken leg/thighs/,breasts, in the cryovacs. and the STL ribs are good, plus it's the only place I've found pork belly,when they decide to carry it.
I'd say on avg. costco is a bit higher in price, Walmart can be a a wild card if their crack employees decide to not restock the shelves, both places can be crowded, service at costco is good, walmart can't spell "service."
They both, and the supermakets, have their place, so a membership isn't a bad thing, but I can get by without a Costco.