Pros
Job requirements will usually be made clear, up front. If you can keep your head down, fly below the radar and continue to do what is required of you, you will survive. You may need to be flexible and willing to reinvent yourself, perhaps relocate, to avoid job loss as work is outsourced, moved to centralized locations, and jobs are cut.
Cons
Large, slow bureacracy makes it difficult to make a true difference as an employee. The company meets the letter of the law in dealing with its Employees, Customers and Shareholders, but all three groups of stakeholders are being treated with less and less consideration as the firm grows larger. Employees in all areas of the company that I encountered are being forced to take "do more with less" to an extreme, as co-workers are cut and not replaced. My impression is that the firm is paying less than it used to for the same work, requiring more hours and/or more work from each employee, and finding inventive ways to push higher-paid, longer-tenured employees out the door, to replace them with new, cheaper help.