"I felt Newcastle could have dealt with it a little bit better to be honest," he has said.
"I am delighted to be here now it is great opportunity for me," he said.
"It is nearly 12 years of my life, it is a long time and I would like to thank the supporters for the support they have been given me over the years.
"I just felt after being there nearly 12 years, and the service I gave the club, the regime could have looked after the whole thing a little bit better and they made me do things I didn't want to do in the end.
"I felt this was a great opportunity to further my career and hopefully go and possibly go and pick up some silverware and I felt they could have dealt with it a lot better and I was disappointed the way the regime handled things.
"It is a difficult time for Newcastle they are in a difficult period and the fans deserve better they are extremely loyal supporters and I wish them well.
"This is a new chapter in my life at Manchester City and I am very excited and looking forward to the challenge."