Speaking after Thursday night's Europa Conference League defeat to FK Qarabag, he said: “The biggest thing is coming somewhere you want to – and playing games.
“This seemed the perfect place for me.
“I was straight up on Thursday. It ended up being a six-and-a-half-hour drive, which wasn’t great, but at least I got here. I got to see the stadium rocking, the fans were unreal and I’m really happy to be here. It was unbelievable. Obviously it was the first time I’d seen the stadium, and the fans were great. Hopefully there’s more of it this season.
“The manager used to play for Newcastle, and I’ve heard great stuff about the club, and the football they play. He’s experienced Newcastle, knows what it’s like, and I’m really looking forward to working with him and his team.”
Longstaff spoke to United team-mate Ryan Fraser, an Aberdonian who started his career at Pittodrie, before joining the club.
“I spoke to Ryan Fraser, who obviously came through the set-up here, and he just said it was a great club and if you get the chance go and play there,” said Longstaff. I didn’t need much persuading other than that.
“What you want as a player is to be playing under pressure and to deal with it. At Newcastle there’s an expectancy to play at a high level. I’m expecting the exact same thing at Aberdeen.
“Whether that’s playing a little further back and getting on the ball, or whether it’s breaking into boxes and scoring goals, I’m happy to do either.
"Like he said, if I can chip in with a few goals, it’s going to be great, so I’m looking forward to it.”
We’ve gathered the best of today’s Premier League speculation below…