The rookie quarterback could start the Buffalo Bills' opening game of the 2013 NFL season if he has fully recovered from a knee procedure.
Gruden, who won a Super Bowl while coaching the Tampa Bay Buccaneers, told the Bills' podcast: "First of all what impresses me the most is the kind of kid he is. He's got a charisma about him a vibe about him that's just contagious.
"You like being around him. You feel enthusiasm and knowledge and excitement. When you sit next to him you see how big he is. You understand he has a lot of talent. I think he has a huge ceiling and Buffalo fans have a lot to be excited about.
"You can drop him straight back to pass. You don't even have to block anybody because if you miss a few blocks he can still turn it into an explosive play. That's how talented he is."
Manuel was the only quarterback selected in the first round of this year's Draft.