Pros
It's hard to completely dislike Zimmerman because they are one of very few companies that will open the door to a career in advertising to a person with little to no experience (especially kids just out of college).
Cons
On the con side, the company (and surely the CEO) are very aware they are giving these inexperienced employees this opportunity and will use it to their advantage, to the point where it seems borderline unethical. In the Account Coordinator position, I worked late into the night often. Working long hours wasn't really the problem, I was okay with working hard to climb the ladder. There was just no ladder to climb. They worked us to the bone with no real opportunities for advancement and a bottom of the barrel salary which caused really bad team morale.