It's not so much that's she's great, rather it's many peoples only option. Not everyone drew Sol or Amaterasu. Nike can only get you so far now that Ultimate has been included so a strong healer is a requirement unless your team is extremely strong they can take out bosses before you take major damage.

Though as nice as her revival skill is, the main reason to get her is the amount she can heal. Having the ability to revive is nice and all but if you never have anyone dying in the first place, then it's a wasted skill, which could be said for pretty much most character, though it's kinda ironic for her considering she's suppose to be the top healer soul, which is suppose to keep your party from dying in the first place.

I would highly recommend you at least get Cassiopeia then move onto Andromeda when you start needing bigger heals.