Pros
(For the IT org): Really solid training opportunities, good onboarding, good company culture, truly decent and basically good colleagues. The comp, benefits, vacation, etc., are fairly standard. Start before New Years, and you'll pick up nearly a full year toward your vacation increase at 5 years (effectively waiting only 4 years to get that extra week off). IP is a steady and predictable employer, and managers generally do their best to ensure a happy, healthy workforce. If you're willing to go out on the limb, branch out and learn a new position, you will usually be encouraged. They're big enough to absorb your vacancy, meaning you're usually 'releasable' to another manager for internal moves, and standouts are recognized. Shared Services model in IT allows if not encourages cross-pollination and syntopical learning. You can be silo'd if you choose to be, or you can float positions every couple of years if you like. It is unlikely that a solid worker would be downsized, as efforts are made to retain 'people', not just positions. I had an excellent experience at IP, and would return w/o hesitation if the circumstances making that feasible arose.
Cons
If you really dig in and stick to a particular specialty, then advancement can be slow. In big, stable companies, many other employees realize when they have it good as well, so without standout performance or a few lateral moves (to round out technical and business experience), advancement might take a while. IF an individual thrives in a churning environment, then a smaller company with less process and planning might be preferred. The truly restless acheiver might feel stagnate, but again, a change of position and new learning is one way to keep things interesting w/o changing companies. IP is big enough to sustain some employee drift within the organization. If I had it to do over, I would have 'drifted' through more roles.