First-half goals from Marcos Alonso and Jose Basanta after Gonzalo Rodriguez's opening penalty effectively killed the tie after 22 minutes, while Salah struck the crossbar and post on the end of dazzling solo runs in the second period.
The Egyptian winger joined Fiorentina on loan in January as part of the deal that saw Juan Cuadrado move to Premier League leaders Chelsea, and Montella is delighted with how quickly Salah has adapted to Serie A.
"So far perhaps we got the better end of that deal," he told Mediaset Premium.
"We knew Salah's characteristics, but didn't expect him to have such an immediate impact in Italian football.
"Perhaps only Leo Messi is quicker than him with the ball at his feet."
Montella also paid tribute to the mental strength shown by his team in a clinical collective performance.
"The win was deserved and this team has grown so much in terms of mentality," he added.
"The side showed how much it wanted this result.
"We've been through a shocking run of fixtures and come out well. Soon there will be another and we keep fighting for our objectives."
