Ventajas
If you are related to the owner, or one of his cronies - then things will be great. There are some nice people working there. Interesting technologies and projects, when the right contracts are won.
Desventajas
Low wages, and you will be "low-balled" and taken advantage of even more if you are out of work/laid off when you apply. Personnel are not reviewed annually or on any regular basis at all. Some people have gone over 10 years making the same rate. People are working with toxic substances, sometimes without adequate training and knowledge of their rights. Friends and relatives are promoted to positions of authority, but may not be qualified. Many workers are generally disrespected; and there is little chance of growth. People driven to do better, improve or change things are pushed out.