Things I appreciated
1) For a good chunk of the movie, I felt it was trying to give us the narrative from the POV of being in Harley Quinn's head. Here's the story, wait, let me go back 4 minutes, wait, now let me go back 1 week, wait, I'm getting slapped so now we're inside my head and I'm Marilyn Monroe. While I could appreciate this approach, there are scenes in between that didn't match the tone, or we cut to a scene that was too serious, or one that didn't matter like Black Mask talking to Black Canary about his art collection. Why did that matter?
2) Most of the fight scenes had a good mix of choreography and feeling real world. If there was any wire work, it wasn't obvious to my eye. Compare these scenes to every-time Rey Palpatine leaves the ground in TROS -- it's blatantly obvious wire work, distracting, and pulls you out of the movie. This was not the case in Birds.
3) The title cards when a random character came out of nowhere who had a grievance with Harley was good, but again the contrasting tone with other scenes didn't match the overall tone making the "toned down" scenes boring or confusing. Also Black Mask yelling at the random girl in his club to dance and strip. What was that about?
As for the rest...
Why is this movie called Birds of Prey? Black Canary is a bird, but what about Huntress and the cop? Is birds in this case a use of the British slang for a woman?
I feel this movie wanted to focus on Harley Quinn, because that's who people want to see, but unfortunately she had the least interesting storyline.
My only experience with Harley, other than Suicide Squad, was Batman The Animated Series. If Joker kicked her out, I feel that she would do what she could to get back in his good graces. Maybe capture Batman or Robin or Batgirl or something and present them as a present to Joker. This would make the Joker happy and then they'd make up. But this movie was committed to Harley going out on her own, so because of that she causes her own problems.
Then while she's dealing with her problems, we get mostly Black Canary who is pretty uninteresting. Huntress randomly pops up here and there and she's also pretty uninteresting and one dimensional. The pick pocket girl didn't add much either. There was a lot of focus on the cop getting a raw deal but I didn't find myself caring about her either.
Back to the Animated Series, I appreciated Harley having a pet hyena. I'm sure there were other Easter Eggs from the show that I missed.
Margot Robbie can definitely carry a movie, unfortunately her emancipation alone could not fill an almost 2 hour movie, so they need to add other "stuff". The stuff they decided to add concerning the Birds didn't get me to the point of caring about the overall story and once they were finally together, they tried for some more comedy amid the chaos where some landed and some didn't. I wish this "girl power" movie had had more power.
In summary, it felt like it was trying to and wanted to be "Deadpool" and I wish it was, but it never got there. I was very bored at times and comparing this to Suicide Squad - I had more fun during Suicide Squad. Most of my blame on why I didn't enjoy this movie would be on direction and tone, so I mostly blame Cathy Yan.