Not sure what your area was or what, but it's definitely way cheaper. I still have the ability to go and make a 45-minute monthly trek to do so. Meat alone is, on average, 50% cheaper than Walmart and about 30-40% cheaper than the cheapest place I have in town

There are a few exceptions like certain canned veggies/beans if you can buy in bulk at Sam's Club or Costco can be a bit more expensive at the Commissary on a per ounce basis and name brand frozen/pantry "convenience" foods tend to have little savings

But by and large it's dirt cheap compared to off-base