Well, This movie in a way is very similar to part 1, however crew became oblivious that audience already knew that the girl has supernatural abilities, so there is no surprise element. Also the power is of great magnitiude compared to part 1, so it becomes like animation.

More characters leads to less depth of characters. The Girl is just a blank paper (She gets 8 to 10 Dialogues overall) and JaYun gets very less screentime as well.
JaYun saves her friend in part 1, here the Girl did not save 2 people and exhibits enormous power later which she could have used earlier to stop those bombings. The other is not shown as smart like the former one, she used excessive power on those gangsters when its unnecessary.
Genetically modified people are not only known for their physical power but also they are considered as smart (in all aspects) in understanding the situation and dealing with it. Also surprisingly Girl never had any objective in her mind.

IMO , I would recommend to to use limited power (Otherwise it would become like X-Men )
Note the comments are about the Plot and ACTING wise Everyone did an exceptional job !!