Pros
For a company as large and widespread as REI, I was tremendously impressed with how interpersonal it felt. I always feel as if my manager really does have my best interest at heart. As a student, it is particularly wonderful to have the flexibility to pursue my studies and balance my life between work and play, and still have a great job. Definitely take the "work/life balance" aspect of employment very seriously. Benefits are fantastic - we're all gearheads, and the discounts and prodeals are wonderful.
Cons
While REI likes to see itself as hiring "inspired guides," the truth is that the company often times feels like it's holding its employees back from really enjoying the outdoors. This has gotten better thanks to the "Yay Day" initiative - designed to give people paid time in the outdoors - but it has felt like it can be hard to actually use the gear you're selling. As a retail position, the only real ways up are either to make the (difficult) jump to headquarters, to be willing to move about the country as a sales manager. Managers often spend years jumping between states and stores.