Pros
Thorough training before and during your first few months. I was working front line and even after training managers cut me slack if I made a mistake during my first few months. My coworkers, for the most part, enjoyed working at REI and were mostly satisfied, this made for a more enjoyable work culture than other places I've worked. My coworkers were also quite supportive and I felt like we could work well as a team. My bosses never gave me too many unrealistic tasks to accomplish each day, that really takes the stress down a notch when you don't feel overwhelmed. I loved the annual Christmas gift and the great discounts! I appreciated being able to say via the availability form, "never schedule me on Sundays" and they always followed that. I'm very grateful for that. Also, I always filled out my time off requests well in advance and was always granted my requests. Most of the customers I encountered were happy to be at REI and so, compared with other retail stores, I had very few angry customers to deal with. I would work at REI in a heartbeat if it weren't for one thing (see below).
Cons
When I applied for my $11/hour part time job there were 9 positions available at the store in question and hundreds of applicants had applied. There then followed a rather lengthy hiring process considering the relatively meager salary. The cash registers (at least at my store) were dinosaurs and the user interface was far from efficient or intuitive. Most of my bosses were amazing: open, communicative, friendly and didn't gossip. I did have one boss who chided me in front of a large group of coworkers and didn't seem to think very highly of me. I was able to avoid him for the most part. The real reason I left? I wasn't selling enough memberships. During training they say that it's important but that they understand if you're having troubles. What they don't tell you until later is that they rank each employee based mostly on their membership sales. If you're at the bottom of the totem pole--your hours get cut. The pressure of having to sell memberships when most people are already members was too much for me. I'm not a salesperson, it's not my gift and it stressed me out. If you're a good salesperson and can talk even the most resistant of folks into buying a membership then I think you will love working at REI--it's a great place to work apart from the membership pressures.