Vantaggi
It is large enough that you can network with literally thousands of people. I'm a firm believer that a company's worth is measured by the quality of the people who work there, and GE inherited (through several acquisitions) some truly dedicated professionals. There are always opportunities to advance, since (in my tenure) there was a lot of turnover.
Svantaggi
For such a large company, I was surprised by the absence of processes when I joined. I have worked for family-owned businesses that took better care to provide computer backups, for one example. Promotions often seemed overly influenced by the "diversity" of the candidates (as opposed to their qualifications). I was verbally discouraged by one HR manager from applying for a job because I did not have the pair of chromosomes they wanted.