The former Galway teen penned terms with the Magpies this week.
Glynn, a former Newcastle trialist himself, told ChronicleLive: "When you're playing international football and because he's an attacking player, when he gets on the ball, he's one of those players who excites spectators.
"You can see there's something about him.
"Because he was so good on the ball, he would go down either wing. We used to play him a lot inside, as a 10, to develop his game a bit further. He took to that very naturally. He's a very intelligent footballer. He makes the right decisions very quickly. He's athletic. He's very lean and has loads of scope for development physically.
"Going from a part-time environment to full-time is the biggest difference. You need to have a lot of mental strength and he will gain even more now in the new environment, but it might take time."