Again, I'm very used to the P&G 3 key points. So here are my top 3 downsides:
(1) Generally a risk averse company, so there are LOTS of processes to help mitigate risk which take time to take things to market. Yes, its good to be prudent, but not if it takes forever and by the time you launch, competition and everyone else has beat you to it.
(2) Doesn't really foster great experimentation / innovation. If you want to change things, you better be prepared to fight fight fight, rationalize rationalize rationalize, lobby lobby lobby! It will get there in the end (it's been done before, but please be patient).
(3) We work like investment bankers/consultants, are in fact probably even more accountable (ie. we don't pass on decisions/risk to clients), but yet we aren't paid as much!
(3)