Pros
Great benefits including fully paid medical, dental and vision insurance (depending on which plan you choose). Jobs are available doing almost anything you can imagine since the company is so large. Also there are a very wide variety of programs and locations. The work is fairly stable compared to many start up businesses.
Cons
Union membership is required (for engineers in certain regions like the pacific northwest). Structured hierarchy for job levels doesn't leave much room for advancement. In other words advancement is largely dependent on years of experience not necessarily skills. Vacation is very limited until you have been at the company for a long time. For instance you only get 10 days a year until you have 4 years of service. And you max out at 20 days per year.