Pros
Boeing is one industrial leaders in the commercial airplane and defense sector. There are opportunities to work on the latest and the most cutting technologies up to date. Also, if you don't there like your position, there are tons of others that you can transfer to within the company. Since there is an employee union (SPEEA), it is almost impossible to get fired. (Not all engineers are part of the union, depends on the location). The union negotiates competitive salary and benefit package for the employees. It is a pretty safe and secure job if all you want is to get paid.
Cons
Since the company is so big, one is really hard to stand out or make a difference within the company/group/division....etc. The company is old and has its build-in culture and bureaucracy that will never go away. It is very hard to change things for the better. A new employee starts with only 80 hours of paid vacation for the first 5 years, 120 hours of paid vacation for 5-16 years, and stays at 160 hours of paid vacation after 16 years. The company always tries to take away or reduce the benefits from the employees. The food offer at the Boeing cafeterias are awful, expensive and unhealthy.