MEC is THE place to go when you need to get anything camping/hiking/backpacking (and any other outdoorsy active thing)-related. I gave a 5 because the customer service at MEC is my benchmark service at any type of large store.
Customer service is top-notch. There is always someone there that's willing to help and answer any questions. I was buying a backpack for travelling and the retail associate answered all my questions, offered many options, stayed within my budget and even filled my backpack with weights and let me walk around the store with it (to make sure it was comfortable for me). This is just one of the many positive experiences I've had at MEC.
I think that the key to getting this superior customer service is to go when everyone else IS NOT. This will include Saturdays, lunch hours and immediately after work. The hours here are pretty reasonable, so it shouldn't be hard to go outside of the above times.
GO HERE if you need any camping/outdoors-related supplies - even if you're not sure what you need, there will be someone that will be around to help.