Fresh. The crowd control methods employed (refer: non-lethal colour blasting grenade), the chases, the dialouge deliveries, even the designs of the hideouts and other settings; the direction overall is definitely what you'll find a bit different from the recent movies of the superhero/villain genre.
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Margot Robbie as Harley Quinn, who serves the best combination of the traditionally expected cute+sexy+psycho+cheerful outlook with her newly inculcated feelings of camraderie and metorship was definitely the centrepiece of this film, unlike in the Suicide Squad.
Cathy Yan succesfully managed to pull off a fun superhero movie with zero male protagonists without it coming off as some 'female empowerment social programming'.