I work a bit on the side for Costco. I probably don't have the full feel as 1) I've never worked full time retail and 2) I don't work very often.
What I can tell you: closed sundays and holidays. Good if you don't like working either of those. Bad if you want to make time and a half working holidays. They give you an employee handbook, it reads like a union contract...benefits/working conditions are better than if you're not in a union. They're worse than union jobs and much worse than any hospital I've worked in.
The workflow is poor. The store I'm at is slower than most community pharmacies I've been in, but I always feel like I'm working more. The techs do not like moving around. I'm constantly trying to get someone to count pills for me. Could just be my store is badly managed; I don't work with the full time pharmacists, so I don't know what goes on when I'm not there.
It is impossible to ban a rogue patient. Had a friend who had someone throwing used syringes at him (more than once). Eventually, he was able to get management to ask him to fill his prescriptions somewhere else. They would not revoke his membership/ban him from the main store as he was a $10k+ a year member.
You'll feel more appreciated than at a regular chain. Most employees genuinely like working there. The main complaint is they can't get enough hours (that's on the floor, not the pharmacy).