Generally it's a slow job, and when it's slow, it's pleasant. You can have nice, brief interactions with customers, and take care of things quickly. When nothing comes through, one can read (or write!) and mark the time until the next donation arrives. Sometimes it'll pick up, and when it does, things pile up and the job can become stressful. There's no means to tell what kind of day it'll be before you come in. 10 hour days.
Pay is low. From my experience, there's no raises, and no upward movement. A full-time employee won't make enough for rent, so I'd only recommend this to younger people who can still live at home, or bored people with a spouse/partner who already provides. I certainly DO NOT recommend this to anyone who needs enough money to live on.
If you're a depressive person this job gives you just enough time to think about how sad you are and how you wish you had more money and were doing more.
Management was aloof and uninvolved for most of my tenure, but this is changing. The new manager actually takes their job seriously, and it's appreciated.
Decent life/work balance, Paid holidays, Usually relaxed
Low pay, No promotions, No raises