Pros
Reasonably good job security against layoffs in current environment. Decent pay after a few years in the trade. Minimal work expectations, there's never an urgency to get anything done, if you do not do it someone else will. If you end up on a good crew or play the EB game right you can rapidly advance and even become a boss in a couple years. Maybe faster than you could at McDonald's.
Cons
Union representation does nothing to protect against disparate treatment from management for most people. It is very important to maintain popularity and not rock the boat. Extremely risk averse culture. Doing things better is actively resisted. Taking the initiative is penalized. Advocating for yourself can get you black balled. If you have a good work ethic or take your job seriously be prepared to be slowly crushed over time. What you earn or what you do seemingly has little connection to your effort, work product or capability. If you are an hourly employee expect to be treated like a child or animal. Sometimes the work environment is dangerous or unhealthy Rather than everyone working as a team cliques for and people try to put others down so they can advance despite the nominal union shop. Where you work is luck of the draw. Job responsibilities very greatly between areas and shifts. Management can move you to another area or shift whenever they want for the majority of people. If management doesn't want to have you working for them they can make you disappear. There is no union security. The majority of people are less qualified than mechanics or millwrights working anyplace else but that works at EB because most people don't do much and there is no urgency to get things done. You are a storm trooper not a Jedi. Every job has too many people on it.