Pros
Job security (pretty much). If you do well and get hired, you have a job for the forseeable future. Also if the economy takes a tumble, you can count on your retirement program surviving very well. You can also look forward to that for decades to come; P&G execs have no need of pulling an Enron, MCI, Globodyne (Fun with Dick & Jane), imclone, etc. The top execs will not abscond with loads of money while leaving thousands of employees broke. There are many other perks too besides the great healthcare/daycare benefits. Usually you get gift packs delivered by Christmas, bonus store items, consumer panels (compensated opinion surveys), free product, etc. etc. There's also King's Island days/giveaways. P&G generally keeps you challenged.
Cons
There are politics and lots of them, so get used to it. Even as an intern, if you get the wrong boss, chances are you won't want to come back. If it's your first job experience of any kind after high school/college, do NOT think that all companies are like this.