Pros
Boeing is a world class company that invests in the training and resources to enable employees to do their jobs well. I have worked at other large and small aerospace companies. Boeing, by a far margin, has its act together the best of them all. There is never a lack of interesting and challenging programs and jobs available to capable employees.
Cons
You can get pigeonholed into a position that can limit your mobility within the company. Senior engineers are encouraged to take lead positions that might be too much work for the individual or be outside of their expertise or ability. Also, occasionally the wrong person rises into management who turns a group into a toxic fiefdom that is a gulag of overtime, unmet unreasonable expectations and poor performance reviews. To Boeing's credit, those managers do not last too long and often find themselves taking non-management positions.