Pros
R&D should by nature involve learning new things, and P&G promotes this with a system of "Communities of Practice" (for example, Skin & Hair Science, Packaging, Polymers, etc) and symposia & training sessions from both internal & external experts. P&G people generally have good ethics. Great maternity leave or "less than full time" options, so if you value work-life balance more than maxing out your paycheck, you & your manager can probably figure out how to get what you want.
Cons
Salary is fair but not highly competitive, and anything BUT transparent. Based on experience at 2 other companies before working here, I'd say the depth of the talent pool is clearly above average at P&G, yet the company rating system requires a quota percentage of employees to get poor rating (3). That doesn't necessarily mean a 3 rated person will lose their job, but raises & definitely all promotions are out of the question, and I'd assume it would also make lateral transfers to other projects or jobs difficult. This potential problem is magnified by the tendency of 1st & 2nd level managers (section heads & AD's) to play musical chairs in the company. I've seen cases where employees have had 4 section heads in just over a year. Your rating will depend largely on how well your manager advocates for you in the rating sessions comparing you to peers among other managers' employees, so too many re-orgs or managerial musical chairs could hurt an employee's chances for a good rating, even if they do really good work. There are tons of specialized systems that you need to navigate in order to do things, and overall P&G can be fairly bureaucratic or schmoozy at times. It makes it very hard to deliver new products quickly. There was much less need to schmooze or navigate bureaucracy at the most upstream research facility (MVL), but unfortunately that facility is being shut down. P&G also seems to buy into their own hype too much - we usually assume our version of a product is better than any of our competitors, which can make it very hard to see our weaknesses or areas where competitor products are better. The greater Cincinnati area is very conservative & very evangelical - there are even some P&G scientists who support the nearby "Creation Museum" in Kentucky.