By and large, I love this Costco location. The bakery staff are friendly and handle special requests with aplomb, the selection of products is great, and all the photo lab technicians are top notch. They also always have great looking cuts of meat at the butcher shop.
Being located just off the freeway also means it's easy to get to from almost anywhere in the East Valley.
My only gripe is that the members only gas station is hardly cheaper (only a couple cents) than local stations. Gas prices at the Gilbert Costco are much lower than the Chandler Costco, despite chain gas station prices being similar near both stores.