Pros
Fellow staff members are a joy to work with, things generally feel fun, supportive, and cooperative. They really make the job worthwhile. Positive interactions with owners and pets can be really rewarding, feels good to make a difference in their lives and share your knowledge. Management is slightly more lax than other retailers, will make accommodations, and leads show they want to help you succeed.
Cons
Underpaid for the work and expertise that is needed. Not only do you have the challenges of a typical retail job (which are underpaid as-is) but need to learn in-depth knowledge on pet nutrition, health, and behavior as well as a huge catalogue of different foods and products. This knowledge base is extremely valuable and employers should be paying more to keep well-educated staff on board. On the corporate side there is a lot of emphasis on expansion instead of investment in existing stores and staff. Occupational hazard of poorly behaved dogs which although rare can be very stressful.