Again, two words can be used to describe the downfalls of the company:
1) Complex
2) Conservative
Complex: All large corporations are complex by definition, but P&G's matrix hierarchy design makes things extra difficult. For example, I have one direct manager that I report to, and he has one manager he directly reports to, but he also has 2 other managers that he "indirectly" reports to. This is an outcome of the collaboration and teamwork within the company (a good thing), but sometimes it can be difficult to get internal alignment because of this. This complexity also bears out in the work processes, especially in budgeting and finance issues.
Conservative: The company is extremely conservative. I am not saying they are not cutting edge or visionary, because they are, but they only like to make decisions when they have tested the idea out and are almost 100% it will be successful. This is likely one of the reasons for their success, but it can also lead to losses when a competitor gets a good idea, rolls with it, and beats P&G to market. This conservatism also leads to barriers internally because you have to "prove" almost everything you say with data... and the reality is that data is not available for every business decision that must be made.