Pros
Cargill has a noble purpose of nourishing the world, and strives to be the partner of choice. It's global reach and perspective is fascinating and if you choose to seek out exposure to this it can be very rewarding. The people are for the most part amazing- some of the best folks you can find. The company takes it's guiding principles very seriously, so you can have confidence you're working for an entity that is on the level ethically.
Cons
In many ways, Cargill is not a meritocracy. You may work very hard and get results, but when it comes times for promotions it may matter more who you know than your track record. This seems to be slowly changing, but can be highly frustrating. There are still pockets of the good-ole boy system alive and well within this company- you find them mostly out in the field, not as much in the headquarters. For years they touted the "Hire to Retire" approach to talent management, however within the last year the corporation has initiated a reorg that has resulted in quite a bit of lay offs. No longer is this the stable privately held company I joined 13 years ago - there is seemingly very little safety or job security of late.