Pros
Usually, if you put effort into working as well as trying to find better positions and wait long enough you can get a better position within the company easily. You can't always be easily fired because this company's employees are all within the union and can find some kind of protection if you search through the right channels. This type of job isn't very difficult if you just pay attention.
Cons
Since this job is fairly simple its easy to get into trouble by goofing off. There is also a lot of favoritism within the company and some are allowed a lot more freedoms than others. Despite some of the positive aspects of the union if there is no participation or well informed people to enforce those rules the managers have a tendency to over step their bounds and occasionally trick you. You need to think on your feet and remember yourself and them that you have rights. Be wary of what your say as well because some will try and make your job difficult and make you quit since they can't fire you.