McGinn put in another excellent display and scored his second goal of the season as Villa recorded a stunning 3-0 win at Derby on Saturday.
The Scot has been a standout performer since joining from Hibernian in a £2.75million move back in August and has wasted little time endearing himself to new head coach Smith.
The boss said: “John has been outstanding. I can only talk about since I have been here but he is a better player than I could have dreamed of.
“He has energy and quality, bundles of it. We are very fortunate to have him.”
McGinn headed the opener as Villa ended the Rams ‘six-match unbeaten run to record back-to-back wins for the first time this season.
His strike delighted Smith, who has stressed the importance of midfield players regularly getting their names on the scoresheet.
Smith said: “Just like against Bolton the previous week we expected John and Jack Grealish to go and get in their box and they did that well.
“John timed his run really well. He had a couple of chances in the first-half as well and it is something we are trying to encourage.”
McGinn said: “The manager has been encouraging me to make more runs into the box because he believes I can score more goals. I agree with him.”