Depends who you are talking about. In the media Pep actually gets all the credit he deserves, they all talk about how he's almost single handedly changed English football and he's the first person mentioned above any player when talking about Citys success.
If you're talking about rival fans, then you'll be in for a long wait. it's simple bitterness and jealousy that they don't have the greatest manager of the generation and possibly ever. It's no real surprise they'll grasp on to any little sliver of doubt and play down his genius because ever single one of them would kill to have him as their manager.