A five-wicket victory for India on Wednesday secured a series win for the hosts, but Stewart believes that Root's arrival in international cricket is encouraging for Alastair Cook's side.
The former England wicketkeeper told BBC Sport: "The one big positive to take from the batting is the way Joe Root played in his first one-day international series.
"I picked the young Yorkshire batsman as one of my players to watch in 2013 because he instantly looked at home in international cricket - rather like Graham Thorpe and Marcus Trescothick did when they started their careers.
"I have seen him play for Yorkshire, where he often bats in the middle order in one-day cricket, so I was aware he had the capability to play all around the wicket."
The fifth ODI takes place in Dharamsala on Sunday.