Oh Costco. Love this place! Unfortunately the days I usually go are Saturday mornings, so it's my own damn fault when I find it difficult to move around, or when waiting in line for an exceptionally long time.
There's not really much to complain about Costco and the items themselves, nor their quality. Yeah once or twice those triple chocolate cookies weren't that great, but beyond that I've never had a problem there. Their clothes section tends to be pretty messy (customers fault, not Costco's) but the stuff they have is nice, organized underneath the mess, and with a decent stack of sizes. The samples are also always lovely and the people running those stations are quite efficient at trying to make sure they don't run out of samples.
If you look past the lines, the service at the cash desks is exceptional. They have most cash lines open when it's busy and will have one person to ring items through, and another to pack. One time while shopping here with my mom we only had about ten items in the cart, and someone offered to ring through our purchase while we were in line since we weren't buying much. When we finally reached the cashier we gave them our card, and the whole purchase was right there and ready to be paid for. I don't really know what the place could do to speed things up more.
Plus the fact Costco is in a shopping complex just off Deerfoot makes it even more worthy of five stars.