Pros
Union. Benefits. Good pay. Sufficient training. You don't need prior optical experience to work for Essilor, but of course, it's a bonus. You learn a lot about optics and vision in general here. At my location, HR is pretty decent at handling any issues you may have.
Cons
Team leads are questionable and at times, managers are, too. Very family like environment, however, that comes with the cons. Managers get too friendly and need to know when to put their foot down. Because this is a Union job, managers also need to remember that it's not their sole responsibility to remedy or mediate conflict at work. Don't impede in anyone's right to contact the Union when it's necessary to. Given how fast paced the job can be, I think the breaks can be extended to 15 minutes and not just 10. People already take advantage of their break times anyway and extend their breaks to 15-20 minutes if they want to, and management doesn't seem to care much - so, why not just change it permanently?