Pros
There is real investment in employees' personal development and true opportunity to advance to much more senior levels. The "promote from within" ethos means that more is invested in existing employees (and recruiting more great people) and that senior managers are not "flown in" from other organizations. The culture is very focused on results delivered and strong performance is very well rewarded, both in terms of compensation and benefits, but also in new opportunities that you are given to progress even further and faster. Overall it is an absolutely fantastic place to work and if you put a lot in you will get a huge amount out again.
Cons
Sometimes can be a too inwardly focused and resistant to learning from the outside. Huge company, so sometimes there is a tendency to keep doing things "the P&G way" rather than really taking a hard look at whether processes could be improved.