EA did change under his leadership, but it was mostly for the better. He fixed a lot of the problems there. He's a good guy who likes games. He actually plays games. That already puts him ahead of most publisher CEOs in my book.
Nobody seems to remember Erin Hoffman's blog detailing how badly employees were treated, working 100 hours a week with no overtime pay. When Riccitiello came back to EA he made it a priority to fix that, and huge improvements were made.
He established the EA partners program which offered good distribution deals to independent developers while letting them retain intellectual property rights. Almost all other publishers give developers shitty deals and take the intellectual property rights anyway. Crysis, Rock Band and the retail releases of all of Valve's games since Half-Life 2 were distributed under this label, along with many others. I don't think I've heard a bad thing said about it. This part of EA actually operates more like the original vision of the whole company, which was founded on the principle of giving developers the credit and share of profits that they actually deserved.
He greenlit unique games which tried new things in an industry which overwhelmingly favors low risk sequels. I don't think the old EA would have been interested in letting DICE make Mirror's Edge, and even though I don't consider it to be a great game I'm extremely glad that it exists. He also slowed down the rate at which EA would assimilate developers before bleeding them dry and shitting out their corpse. He gave studios more freedom and autonomy.
But while all of that was good for gamers and good for the industry as a whole it wasn't so good for the finances. Turns out that actually paying your employees costs money. His attempts to appease shareholders and get back to the previous levels of profitability without reverting to the old evil corporate ways have been much less successful, and have mostly resulted in a bunch of new reasons to hate EA.
The turn around from good EA to bad EA wasn't down to him. It actually happened while he wasn't at the company, it's just that the general opinion of EA has lagged behind actual events by a number of years. Riccitiello took a lot of blame for the shitty practices of the previous CEO despite the quality and variety of games improving along with employee satisfaction. The previous CEO was Larry Probst, by the way, who'll be taking charge again at the end of the month. If he ends up taking the CEO position permanently then the old EA will return, with improved finances along with all the old problems.
John Riccitiello was not the problem, and I'm genuinely sad to see him go.