Vantaggi
Pay, stability and benefits are second to none for the area. For exempt (salary) staff, schedule flexibility can be great, can be terrible dependent on your management. Annual performance reviews can be positive/encouraging/attainable - again dependent on your management. My last one was very positive, but that was after 4 mediocre ones where I never felt I had full, absolute control of my goals and objectives. I can't say for certain, but I've heard that promotions for engineers are limited based on cost which really only hurts people when everyone does really well. That being said, promotions are awarded based on performance within a reasonable time (4 years for me).
Svantaggi
The bureaucracy can be debilitating. Seemingly common sense decisions can take a mountain of approvals and as such can take forever if one person is unreachable. Certain members of middle management wield significant influence that trumps other departments more often than not to the detriment of the plant.