She is neither braindead or OP. But its always same the people crys and moans because ppl cant stand her same with Christie or Helena. Instead to learn the tools, the strenghts and weakness from that "problem characters" first complain. But thats the humanity thats overall the same.
Free Step Dodge
QueenJakheiho
Brute
she's not OP. And no one is TRULY braindead in that they require no thought process to use/win with. However, Momiji does require far less brainpower and execution than most characters.