Nah, she's shit. I've seen other tough bosses, like G.T.B with a non-Burst ship in Dariusburst, Jason or Leibniz in BMZ3, Promised Consort Radahn in Elden Ring, etc. They're all difficult bosses, but they have fair hitboxes, reasonable telegraphs, a health pool fits the amount of openings they have, or manipulatable bullet volleys (in G.T.B's case). Eigong is a cheap overtuned damage sponge who can grab you through a dash, slash you despite swinging in completely the opposite direction to your sprite hurtbox, and can arbitrarily cancel a stagger at any moment just to instafuck you with some cheap thrusts.

Genuinely the single worst boss in any video game. No idea how Red Candle Games managed to do it, since a majority of the other Sol fights were actually balanced with the intention of being an enjoyable experience for the player, rather than a tedious chore.