"Ricky bounces from hip-hop posturing to sweet naivete, naming his dog Tupac and expressing himself through haikus," he said.
"When he's plopped at this foster home at the beginning, you wonder how his sad life could possibly amount to anything, until his creative spirit shines through and you realise that he'll be okay wherever he winds up.
"In the course of the film, as he warms Hec's cold heart, he emerges as one of the most touching characters you'll see this year."
The praise comes after Wilderpeople become New Zealand's biggest ever box office hit, breaking records with its $1.3 million opening weekend, and topping Boy's total box office takings to claim the No. 1 spot.
It has taken approximately $29.5 million in total box office takings after being made for an estimated $2.5 million.
The praise comes after American reviewers warmed to the film, with Rolling Stone calling it "oddly affecting" and The Wall Street Journal saying it was "wonderfully fresh".
Waititi is currently working on his next film, superhero sequel Thor: Ragnarok, with Chris Hemsworth and Tom Hiddleston on Australia's Gold Coast.