As a former Walmart cashier, I have seen some customers save a lot with the Savings Catcher, and some customers save little with it. It really depends on what sorts of items you buy the most often. I really suggest you check out Walmart's FAQ on the Savings Catcher, especially the "Matching" section that says what is matched and what isn't.
Some customers redeemed their savings every time they saved a couple bucks. Some let the savings rack up to use in very inventive ways, such as an emergency fund for groceries if money gets tight, or to use later in the year on Christmas gifts.
There was one couple that let their savings accumulate and were able to buy their child a $100+ bicycle just with their savings for his birthday.
I'm not a Walmart fan girl or anything. I just think Walmart gets a lot of flack on its own, without misunderstandings about how something like the Savings Catcher really works.
Walmart Pros: Overall a good place to work, Good place to shop, Ad matching.
Walmart Cons: Self check is too impersonal and unreliable.