Pros
I've had many opportunities to learn new things (about animals and how to care for them). Some days, I've spent decent portions of my shift mainly playing with animals. With the exception of one or two people, everyone at my store cares a lot about the animals and does their best to properly care to them.
Cons
Non-managers are usually given very few hours, and (except around Christmas) there are very few people working at the same time. (Most often, there are only three people working a shift. It can get crazy when the store gets busy.) The pay is low, but that's to be expected in a retail job. When working as a cashier or on the floor, you have to stand for hours and hours on end, but that's also to be expected. Few, if any, chances for a bathroom break if you aren't working a long enough shift to get a meal break, especially as a cashier.