Smith says it was tougher leaving Elland Road than walking away from Old Trafford, as he did last week.
In some ways it brough back memories of Andy Cole's move back in 1993, but only in the other direction.
Cole was gutted to be sold by Kevin Keegan, and there were angry scenes outside of St James' Park when the deal went through.
Cole still looked shell-shocked at the press conference at Old Trafford, but later said the deal was for the better.
And regardless what Smith says, Sir Alex Ferguson said two weeks ago Smith was surplus to requirements and he was available for transfer. And that gutted the England international, who had just returned to international duty and at long last hoped to gain a regular first team place at Old Trafford.
Smith told the Evening Chronicle: "Leaving Leeds United was more difficult for me than leaving Manchester United because of the connection I had with the club.
"The time for me to leave Manchester United had come.
"It wasn't because they asked me to go or because I wasn't good enough to perform at that level but because the chances that I was going to get were going to be limited.
"I wanted to go somewhere where I was starting afresh and where there was a new manager in place. The crowd here is desperate for success and players are desperate to live up to that and want to achieve as much as possible.
"It wasn't difficult to sign here and Sam did not have to sell the club to me. Everybody in football knows what a great club Newcastle United is and the fans are fantastic."