It's too shrill and staccato; all the instrument parts are in the upper frequency range. That song basically says to the listener, "It's time to be stressed!!" No thanks.
I think maybe something like Kenji Niinuma's
The Moon and the Prince or
Disco Prince (from Katamari Damacy and We Love Katamari) are probably the only songs I could listen to during battles that much. Persona 3's is pretty good, but after a thousand battles any song can become annoying.
I like the idea of this, but that theme is complicated musically, which creates cognitive load on the brain as it tries to follow the music and the shifting parts. The instruments are played like the notes are being fired at the user. Again, stressful, and tiring for the brain. It's okay if boss music is stressful, however normal battle music should basically have a groove but be something your brain can push to the background, because your mind should be focused on the battle.
p.s. that Fire Emblem Fates battle music reminds me quite a bit of Soul Calibur battle music.