We have got so many close to accurate comic book characters and movies that we can experiment a bit and it's not as if they are very different from what they are supposed to be.
I welcome a bit grounded take on the characters without a world ending scenario with super-villain or a "beam in the sky" type third act. After JL, Aquaman, Shazam and two Avengers movies and it's nice change to see a more grounded movie with small scale action. (Black Widow movie action looks too over the top to me, but maybe some fans like that.)
Black Canary has her super-power the Canary Cry, Huntress's origin is close enough to her comic book origin, and she uses her Crossbow as in comics.
Harley Quinn behaves just like Harley Quinn, this movie takes her further in her character journey, Harley will appear in a different costume again in upcoming James Gunn's "The Suicide Squad" movie.
Renee Montoya and Black Mask are very close to their depictions in comics, only deviation here is Cassandra Cain.