I mean, Ea is okay if you have nothing else. She's one of the worst SSR water himes, unfortunately... that I can at least say without getting shit on.
Ea/Neptune aren't great, like at all... but Ea has potential against rage/stunned enemies, as she gets the rage bar down faster and deals huge damage against stunned enemies. Once awakened, her 2nd skill (6T CD) can give her 30% burst gauge and combo rate up(3T) as well as nullify damage for one turn, so she's not GOD awful. She still has a higher damage output than SR himes, so she's good for beginners!