They don't have as much selection of costco. I also think they are missing some of the programs costco offers such as the auto buying program.
Still though, the prices are great. I easily make up the membership fee just by buying gas. They have great return policies.
For under $4 you can buy a hotdog, drink, and a slice of pizza.
They don't take visa or mastercard credit cards (but will take debit), but costco has similar policies so I can't complain too much about that.
One advantage Sam's has over costco is that it is a lot less crowded.