I worked at PetSmart part-time (More than a year)
They are all about team work. They help you whenever you need. If you work hard, you get a raise every few months. After a couple of years, you get promoted to either management, or a customer lead in your department (the best thing next to management). They offer the highest pay in retail so far and I've worked 4 years in retail, sales, and customer service. It has been my favorite place to work so far of any job I've had.
There were not enough full-time positions available company-wide. The hours are not set regularly. They vary from week to week if you are part time, which didn't work for me because I needed a set income based on my expenses.